Chemistry AQA A level
a basic amino group (NH2) and an acidic carboxyl group (COOH)
what groups do amino acids have
nothing - it remains unchanged
what happens to the enzyme after it has catalysed a reaction
the COO- group is likely to gain an H to become COOH
what happens when the conditions are more acidic than the AAs isoelectric point
the NH3+ group is likely to lose an H to beome NH2
what happens when the conditions are more alkaline than the AAs isoelectric point
a molecule of water is lost and a covalent phosphodiester bond
what happens when two nucleotides join together
H bonds between the bases
what holds the double helix structure together
a polymer of nucleotides
what is DNA
lots of monomers called nucleotides which bond together to form two polynucleotide strands
what is DNA made up of
a piece of plastic or glass covered with a thin layer of silica gel or alumina powder
what is a TLC plate
it binds to DNA in normal cells too e.g. healthy cells replicating frequently and normally like hair and blood cells so stops them replicating as it would w cancer cells. so cisplatin can cause hair loss and suppress the immune system (as controlled by white blood cells) and cause kidney damage
what is a downside of cisplatin
a five carbon sugar
what is a pentose sugar
they have chiral centres
what is a property of enzymes due to them being made up of AAs
-SH
what is a thiol group
a dipolar ion - it has a +ve and -ve charge in diff parts of the molecule
what is a zwitterion
the pH where the average overall charge on the AA is zero
what is an AAs isoelectric point
the part that the substrate fits into so that it can interact w the enzyme
what is an active site
NH2
what is an amino group
use a special plate that has a fluorescent dye added to it which glows when UV light shines on it but where the AAs it covers the dye up so under UV light appear dark
what is another method to show AA spots once separated other than using ninhydrin
cells in the body dividing uncontrollably and forming tumours
what is cancer caused by
a complex of platinum (II) with two chloride ion ligands and two ammonia ligands in a square planar shape
what is cisplatin
when A only pairs with T and G only pairs with C
what is complementary base pairing
enzyme-substrate complex
what is it called when the substrate is inside the enzyme
an NH2 group and a COOH group
what is needed on a protein so more AAs can attach
by using computers to model the shape of an enzymes active site and predict how well potential drug molecules will interact with it so they can quickly examine hundreds of molecules to look for ones that might be the right shape before they start synthesising in the labs
what is one way in which scientists are trying to speed up the process of trying to mind new drug molecules
glycine as its R group is H
what is the exception to amino acids being chiral
distance travelled by spot / distance travelled by solvent
what is the formula to work out Rf values
O = C - N - H
what is the general formula of a peptide link
(NH3+)(R) - C - (COO-)(H)
what is the general formula of a zwitterion
(NH2)(R) - C - (H)(COOH)
what is the general structure of an amino acid
the substrate has to exactly fit into the active site otherwise the reaction wont be catalysed
what is the lock and key model
condensation and hydrolysis
what is the name of the process by which the chains of AAs are joined together and the reverse of it
2-deoxyribose
what is the pentose sugar in DNA
the sequence of AAs in the long chain that makes up the protein (the polypeptide chain)
what is the primary structure of a protein
the peptide links form H bonds w each other so the chain changes shape to form either a sprial (an alpha helix) or a beta-pleated sheet
what is the secondary structure of a protein
the distance moved by the solvent
what is the solvent front
the 3D shape formed when the chain of AAs coils and folds and extra bonds form between diff parts of the polypeptide chain
what is the tertiary structure of a protein
H bonds and disulfide bonds
what makes a protein keep its shape
thin layer chromatography
what method can be used to identify unknown AAs
a water molecule : an OH from the phosphate group of one and a H from the OH group on the sugar of another
what molecule is emitted when two nucleotides bond and where does it come from
AT & GC
what pairs with what: AGCT
the basic amino group and the acidic carboxyl group
what property makes amino acids amphoteric
they have different R groups so all have different solubility in the same solvent
what property of AAs means you can use TLC
the OH groups at the top and bottom of the chain so further links can be made
what property of nucleotides allows a polymers to form
nucleophilic addition of HCN to aldehydes and ketones when the trigonal planar carbonyl is approached from both sides by HCN
what results in formation of a racemate?
sugar-phosphate backbone
what runs down the side of a polynucleotide chain
the two polynucleotide strands spiral together to form a double helix structure
what shape does DNA form
drugs
what substances act as inhibitors
stereospecific
what type of specific are are active sites
2-aminopropanoic acid
what would (NH2)(CH3) - C - (H)(COOH)
near an amino acids isoelectric point
when do zwitterions only exist
a polynucleotide chain
when many nucleotides join together what is formed
the -OH off the COOH group from AA1 and the H off the NH2 group from AA2
when two AAs join together a water molecule is emitted, where does this come from though
next to each other
where are the two chloride ion ligands placed in cisplatin
bc they have 4 different groups attached to the central carbon
why are amino acids chiral
bc for the enzyme to work the substrate has to fit into the active site so if the substrates shape doesnt match the active sites shape, the reaction wont be catalysed
why are enzymes highly specific with what substrates they work with
due to strong C-C and C-H bonds and non polar nature of the bonds and therefore are non biodegradable
why are polyalkenes chemically inert?
bc any other pairings would put the partially charged atoms too close together so they'd repel each other or too far apart or the bonding atoms wouldnt line up properly
why are the only pairings AT and GC
bc of the arrangement and number of atoms in the base molecules that are capable of forming H bonds
why does complementary base pairing happen
so that the bases are in the right alignment and at the right distance apart for the complementary base pairs to form
why does the DNA helix twist
bc the active site of an enzyme is very specific especially if the drug molecule is chiral as then only one enantiomer will work bc the active site is stereospecific
why is it difficult to find a drug molecule to work as an inhibitor
1. All apparatus rinsed with distilled water and then with the relevant solution. 2. Using a pipette and pipette filler, pipette 25cm3 of NaOH into a conical flask. Touch surface of solution with tip of pipette to ensure correct quantity is transferred. 3. Using a funnel, fill burette with acid and then remove funnel - otherwise, some drops may fall through the titration after the initial reading has been taken => lower volume recorded than used. 4. Allow a small quantity of the acid to flow through the burette to ensure jet space is filled. Note initial reading on burette. - If jet space not filled, titre value higher than volume actually added. 5. Add 2-3 drops of phenolphthalein (or another suitable indicator) to the conical flask and place it on a white tile - can see colour change better. 6. Add acid from burette into conical flask, swirling mixture during addition, until indicator changes colour (pink ---> colourless). 7. During titration, rinse sides of conical flask with water ---> ensures all acid is in solution. 8. Note the burette reading. 9. Repeat experiment but add acid dropwise (drop by drop) towards the end point. 10. Continue repeating until at least two concordant results obtained (within 0.10cm3).
(1) Outline how to carry out an acid-base titration.
1. All apparatus rinsed with distilled water. 2. Solute weighed out accurately, on a weighing boat, using a balance accurate to 2 dp. 3. Solid placed in beaker and dissolved in about 100cm3 of water. 4. Weighing boat rinsed with a small quantity of water and washings added to beaker - or, weighing boat should be reweighed and the difference calculated. 5. Solution transferred to a 250cm3 volumetric flask. 6. Beaker rinsed with distilled water and washings added to volumetric flask. 7. Distilled water added to volumetric flask until made up to graduation mark - bottom of meniscus should rest on the mark. - If mark overshot, solution is more dilute than expected => start again. 8. Volumetric flask then inverted 20 times to ensure thorough mixing.
(1) Outline how to prepare a Standard Solution in a Volumetric Flask (for an acid-base titration).
To see indicator colour change better.
(1) Why do we use a white tile?
Water does not react ---> doesn't affect number of moles present.
(1) Why does rinsing the flask with water not affect the end point?
Can be swirled without losing any solution.
(1) Why is a conical flask used?
To ensure that solutions mix and so react completely.
(1) Why is swirling necessary?
- Impurities either need to be very soluble in solvent, as they then won't recrystallise with the product. or - Insoluble in solvent as then they can be filtered and removed before cooling.
(10) During purification by recrystallisation, how do we know if a solvent is suitable?
1. Solid collected by filtration from the reaction mixture. 2. Solid then separated by filtration under reduced pressure using Buchner apparatus. 3. Once solid is isolated, washed using a suitable solvent. 4. Solvent needs to be able to wash away or dissolve any impurities on the isolated product but the residue must not dissolve in the solvent.
(10) Outline how to collect a SOLID product.
Usually collected by distillation of the reaction mixture: 1. Reaction mixture heated and the chemicals that boil at a range close to that of product are collected. 2. Products boil off at different temperatures as they often have different intermolecular forces than the reactants. NB => Consider carefully whether products or reactants boil off first.
(10) Outline how to collect a liquid product.
Dried using a desiccator: 1. Desiccator contains a drying agent such as anhydrous CuSO4 / anhydrous CoCl2 / anhydrous CaCl2. 2. Drying agent in the lower compartment and sample to be dried placed in the upper compartment. 3. Desiccator is then sealed using grease to prevent any water vapour entering, or the air can be removed causing a vacuum.
(10) Outline how to dry the SOLID product.
= Purified by recrystallisation. 1. Crude product dissolved in minimum amount of hot solvent => creates a saturated solution at a high temperature - enables a high yield of product to recrystallise when solution cooled. 2. Solution filtered whilst still hot to remove any insoluble impurities (apparatus must be heated as crystallisation will occur if solution cools). 3. Saturated solution cools slowly to room temperature and then in ice ---> product then crystallises out of solution while other impurities remain dissolved. => Cooling in ice allows an increased amount of crystals to be formed. However, if saturated solution cooled too quickly, impurities crystallise out as well. 4. Solid then isolated using Buchner apparatus and then washed with some cold solvent to remove any soluble impurities which may have crystallised out of solution.
(10) Outline how to purify a SOLID product.
1. Distillate placed in a separating funnel and washed: - Sodium Hydrogencarbonate solution used to remove unreacted acid / acid catalyst. - Saturated NaCl solution used to allow layers of aqueous and organic layers to separate. 2. Separating funnel mixed and then inverted to release any CO2 produced from the reaction of NaHCO3. 3. Layers are then separated in funnel and aqueous layer discarded. 4. Washing often repeated multiple times to ensure all unreacted acid removed. 5. Organic layer is then run into a clean, dry conical flask and a drying agent is added - anhydrous Na2SO4 often used. => drying agent should not be soluble in the organic liquid and should not react with the organic liquid. 6. Once organic liquid is dry - the liquid is decanted off and then distilled.
(10) Outline how to purify a liquid product.
Melting / Boiling point taken: 1. Pure substances melt at a specific temperature which agrees with a known data book value (if sample is known). - Impure substances melt over a range of temperatures. 2. Melting point measured by putting small sample into a capillary tube and strapping it onto a thermometer. 3. Thermometer placed in a boiling tube half full with liquid such as glycerol, and heated, stirring with the rod. 4. Liquid ^ must not boil at a higher temperature than the solid melts, and must not ignite when heated. 5. Temperature at which sample melts is recorded. 6. Experiment repeated, but heating carried out more slowly close to the rough melting point measured.
(10) Outline how to test the purity of the SOLID product.
1. Reactants mixed in a suitable apparatus ---> could be a beaker, conical flask, Quick-Fit apparatus. 2. If reactants are to be cooled, ice bath used. 3. If reactants need to be heated, reflux usually used (with anti-bumping granules) ---> constant heating with no evaporation. 4. Reactions can be heated using water/sand baths or Bunsens - but they have limitations etc as previously mentioned.
(10) Outline practical procedure for the reaction to prepare a pure organic solid/liquid.
1. Side or further reactions - further substitution etc. 2. Incomplete reaction - reaction in equilibrium etc. 3. Some product lost during filtration / separation. 4. Some product lost during recrystallisation / drying. => Can then calculate % yield.
(10) What may affect the yield of an organic preparation reaction?
Some ions form ppts which react with excess NaOH to form solutions = amphoteric oxides.
(11) What do some ions do with excess NaOH?
Important to ensure separation of the different components: - Mixture of compounds may be needed to allow all components to be separated on the plate. - May wish to choose a solvent mixture that dissolves all the components from the mixture.
(12) Comment on the choice of solvent.
- Distance moved by the amino acid should be measured from initial pencil line to the centre of the component spot. - Rf values measured. - Calculated Rf values compared with known Rf values to identify substances.
(12) How can we analyse the results?
Separates different components in a mixture due to differences in their affinities for the mobile and stationary phases.
(12) How does chromatography separate components?
1. Wearing gloves, pencil line drawn 1cm above bottom of TLC plate. = Gloves are important as this prevents contamination from hands to plate. = Pencil used as graphite should not dissolve in solvent. 2. Using a capillary tube, tiny drop of each solution is added onto the pencil line. Plate then allowed to dry. = Drop which is too large may lead different spots to merge. 3. Small quantity of solvent to be used is added into chamber / beaker ---> solvent depth must be below the depth of the pencil line. = If solvent is too deep, sample will dissolve from plate into solvent. 4. TLC plate placed in the chamber and a lid is placed on the chamber / beaker. It is important that solvent level is below the pencil line. = Lid is used to prevent evaporation of the solvent, which may be toxic. 5. Allow process to proceed until the solvent front reaches just below the top of the plate. = Longer plate is often more useful as components with similar Rf values will separate out more - giving more accurate results. 6. Allow the plate to dry in the fume cupboard. = Fume cupboard is used as the solvent may be toxic. 7. Place the plate under a UV lamp as this will highlight any colourless spots. Alternatively, ninhydrin can be used to react with any amines present to form purple spots.
(12) Outline how to separate different species by Thin-Layer Chromatography.
1. Lagging in polystyrene cup. 2. Add a lid to the polystyrene cup. Main source of apparatus error = thermometer ---> can reduce this by increasing the temperature change. ---> can increase temperature change by using a lower volume but higher concentration of solution.
(2) How can we limit heat loss for practicals measuring Enthalpies of Neutralisation/Displacement? What is the main source of apparatus error - how can this be reduced?
1. Plot a graph of temperature (y) against time (x). 2. Before the addition of reagent to solution (0-4 mins): - Join points for first 3 minutes with a straight line. - Extrapolate (extend) line to 4th minute. 3. After addition of reagent to solution (4-12 mins): - Draw a line of best fit through the points between the 5th and 12th minutes and extrapolate (extend) this line to 4th minute. => Temperature change can be measured - distance between 2 lines. Show it clearly on graph.
(2) How can we use a graph to calculate the temperature change (for Neutralisation/Displacement experiments)?
1. Fuel is burnt and the energy released is used to heat a set volume of water. 2. Fuel continues to burn until the temperature of water rises by a set change (20C etc.). 3. Mass of fuel used then measured using a balance. 4. Calculation.
(2) Outline how to carry out a practical to measure Enthalpies of Combustion.
1. Solution is measured out and placed in a polystyrene cup. 2. Initial temperature of solution recorded for a few minutes before second reagent is added (allows temperature to equilibrate). 3. Set, known quantity (mass/volume) of second reagent is added into the solution at fourth time. 4. Temperature recorded every minute until some cooling observed. NB=> Polystyrene cup used to reduce heat loss.
(2) Outline how to carry out a practical to measure Enthalpies of Neutralisation/Displacement.
1. Heat loss to surroundings (air/flask) 2. Incomplete combustion. 3. High temperature changes lead to evaporation of water. => Heat loss can be reduced by adding lagging to the flask.
(2) What are the main errors in the experimental procedure when measuring Enthalpies of Combustion? How can we reduce heat loss?
1. Rate determined by measuring time taken for a set amount of product to be formed. (in this method Rate = 1/T ---> units s-1.) 2. Equal volumes of reactants used in each experiment to ensure time recorded is for same amount of product each time. 3. If ppt formed: - Reaction can be timed until enough ppt formed to obscure a cross on paper. If coloured product is formed: - Another reagent often added to reaction mixture which reacts with product as it is formed to produce a colourless substance. - When this additional reagent runs out, a colour change is observed => reaction then timed until the colour change is observed. => When investigating effect of temperature, the reaction mixture is heated to required temperature - could be using a water/sand bath.
(3) Outline how to investigate how the Rate of Reaction changes with temperature for reactions with NO gas products.
1. Rate can be determined by measuring amount (volume/mass) of gas produced at regular time intervals (every 10/20s etc.). 2. Plot graph of volume/mass against time. 3. Rate calculated by determining gradient of a tangent to graph. => rate would have units based on the units of the axes on the graph.
(3) Outline how to investigate how the Rate of Reaction changes with temperature for reactions with gas products.
1. Enthalpy change of reaction will affect temperature at which reaction is completed. 2. At high temperatures, difficult to measure rate as water will begin to evaporate. 3. At high temperatures, time for reaction is very short ---> increases degree of uncertainty in the timer. 4. Human reaction times will affect the number of decimal places that can be recorded accurately if the times are measured manually
(3) What are some limitations?
1. Total volume 2. Concentration. 3. Surface area of any solid reactants.
(3) Which other variables should be controlled?
- Reacts with other anions (and so removes them from the solution) ---> may also produce a ppt such as CO3 2- /O 2- / OH-. - Many carbonates, hydroxides and oxides are insoluble so would also form a ppt (except those of group 1 metal ions).
(4) In ion tests, why do we add nitric acid before the reagent?
Include: - Liebig condenser. - COLD water in (bottom right). - COLD water out (top left) - Pear-shaped flask. - Anti-bumping granules. - Open top. - HEAT.
(5) Draw reflux apparatus.
1. Bunsen Burner - although should be avoided if flammable reactants/products present. 2. Water bath - good for gentle heating but water will boil at 100C. 3. Sand bath - can achieve higher temperatures than a water bath. Often used in conjunction with a heating mantle. - Sand used to surround reaction vessel and conducts heat into vessel from sides as well => reduces need for stirring.
(5) How can we heat reaction mixtures.
1. Reactants (and products) can be heated together constantly, over a period of time. 2. Components of reaction mixture don't escape from the reaction vessel (as heating causes them to evaporate/boil). 3. Vapour formed is cooled by the condenser ---> condenses then falls back into the flask.
(5) How does Reflux work?
- Can distil a product from a reaction if it has a lower boiling point than the reactants.
(5) Under what circumstances can we distil a product from a reaction?
=> Can apply constant heat to a mixture without losing any of the liquid to evaporation - way of getting reaction to go to completion. => Many organic reactions need to be heated as this supplies the activation energy to break bonds and allow the reaction to occur. ^ Using a condenser allows this to happen whilst preventing the reagents from leaving the reaction vessel (they would otherwise evaporate).
(5) Why are some organic reactions completed under reflux?
- Prevent bumping (sudden release of a large bubble of vapour ---> makes reaction mixture jump up the vessel). - Anti-bumping granules produce many small bubbles, rather than a large one ---> prevent uneven boiling.
(5) Why do we use anti-bumping granules?
- To prevent vaporisation of aldehyde product from the test-tube/boiling tube.
(5) Why does a reaction mixture containing an aldehyde product need to be frequently cooled in an ice bath?
= Pressure (due to gas) can build up and could burst the glassware ---> keeping the top open allows pressure release.
(5) Why does reflux top need to be kept open?
1. Add aqueous silver nitrate. 2. Ppt forms (slowly - slow step is dependant on C-Hal bond being broken). 3. - Cl = white ppt. - Br = cream ppt. - I = yellow ppt.
(6) How can we test for a haloalkane?
1. Rate determined by measuring time taken for a set amount of product to be formed. (in this method Rate = 1/T ---> units s-1.) 2. Equal volumes of reactants used in each experiment to ensure time recorded is for same amount of product each time. 3. If ppt formed: - Reaction can be timed until enough ppt formed to obscure a cross on paper. If coloured product is formed: - Another reagent often added to reaction mixture which reacts with product as it is formed to produce a colourless substance. - When this additional reagent runs out, a colour change is observed => reaction then timed until the colour change is observed. or: 1. Can measure rate by monitoring the change in concentration of the substance over time. 2. Graph plotted and initial rate determined by tangent to curve at t=0.
(7) Outline how to measure the Rate of Reaction by the initial rate method.
1. Rate can be determined by measuring amount (volume/mass) of gas produced at regular time intervals (every 10/20s etc.). 2. Plot graph of volume/mass against time. 3. Rate calculated by determining gradient of a tangent to graph. => rate would have units based on the units of the axes on the graph.
(7) Outline how to measure the Rate of Reaction using a continuous monitoring method - Gas product.
1. Sample removed at regular time intervals from mixture and then quenched with another reagent. 2. Other reagent may be something that reacts with the catalyst, or dilutes the solution so the rate is effectively reduced to 0. 3. The mixture is then titrated to determine the number of moles present in the sample which was removed.
(7) Outline how to measure the Rate of Reaction using a continuous monitoring method - Quenching method.
1. Temperature. 2. Total volume. 3. Concentration. 4. Surface area of any solid reactant. => Often used to help determine the order of a reaction with respect to a reactant.
(7) Which variables should be kept constant? When would this method be often used?
= When the reaction reaches 0.
(8) Under what circumstances would the cell EMF drop towards zero?
1. Set volume of acid pipetted into a conical flask. 2. Alkali added 1cm3 at a time. 3. Mixture stirred between each addition. 4. pH measured and recorded after each addition. 5. As equivalence point approaches, the alkali should be added dropwise to allow for a more accurate determination of the equivalence point. 6. Once equivalence point passed, alkali is then added 1cm3 at a time until it is in excess. 7. Curve of pH (y) plotted against volume of alkali added (x) 8. Find volume added at equivalence point. 9. Halve this value to calculate the volume at half-equivalence. 10. Use the curve to read off the pH at this volume = value of pKa. ---> at this point, calibration curve used to adjust meter pH to actual pH.
(9) Outline how to investigate how the pH changes when an acid reacts with a base. Determination of Ka method.
1. pH meters first calibrated as after being stored for a while, the meter does not give accurate readings. 2. Using a series of buffer solutions with known pH, we record pH meter reading. 3. Simple calibration cuve plotted - pH meter reading vs pH of buffer solution. 4. Once pH measured - the calibration curve is then used to calculate the true pH. 5. pH meters can also be calibrated by using a small dial on the meter (although this can be a little fiddly).
(9) Outline how to investigate how the pH changes when an acid reacts with a base. pH meter method.
To nearest 0.05cm3 - 24.40, 26.35 etc. Rough titrations should be recorded when calculating mean titre (calculated to 2dp).
(Notes - 1) How precisely should we record burette readings? Comment on use of rough titrations.
Temperature = to 0.1C. Time = to nearest second. Masses = to 2dp.
(Notes) How precisely should we record: - Temperature? - Times? - Masses?
Heat until constant mass.
(Other 1) How can we ensure that the (mass change) experiment has gone to completion?
Include: - Bunsen. - Tripod. - Pipe-clay triangle. - Crucible. - Lid. - HEAT.
(Other 1) Outline apparatus - diagram.
1. Crucible weighed on a balance and its mass is recorded (mass 1). 2. Some sample placed in the crucible. 3. Crucible and contents reweighed on a balance and its mass recorded (mass 2). 4. Sample heated strongly in Bunsen. 5. Crucible and contents reweighed on a balance and its mass recorded. 6. The sample heated and reweighed until mass no longer changed ---> ensures reaction completed.
(Other 1) Outline how to carry out a mass change experiment.
1. Formulae determination. 2. Water of crystallisation. 3. Decomposition.
(Other 1) What things would we use mass change experiments for?
1. Set up a known mixture of COOH, -OH, H20 and dilute HCl / H2SO4 (dilute strong acid catalyst) 2. Place the mixture in sealed tube to ensure that none of the reagents evaporate. = Some of ester (species with lowest bp) may evaporate ---> would disturb eqbm to RHS leading to a higher Kc value. 3. Leave mixture for a some time to allow eqbm to be established (one week). 4. After one week, a further tube can be set up and titrated to determine this is long enough - results would be same. 5. Prepare control using only dilute HCl. 6. Once equilibrium established, mixture poured into excess water - "freezes" equilibrium for a short period of time. 7. Sample of mixture then rapidly titrated with standard NaOH solution. 8. Titration results give a measure of total concentration of acid in equilibrium. 9. Titration of the control allows [HCl] to be determined. 10. Eqbm [CO2] can be determined by calculating difference between n(acid) present in 2 tubes. 11. Provided the initial concentrations of CH3COOH, CH3CH2OH, H2O and dilute HCl are known ---> eqbm [ ]s can be calculated. => Can calculate a value for Kc for the reaction under the conditions of the experiment.
(Other 2) Outline how to calculate a value for Kc (for an esterification reaction).
1. Solution placed in a cuvette (small vessel) which is placed in the colorimeter: = Solution may not have intense colour = suitable ligand can be added to intensify the colour. 2. White light from a suitable source is passed through a filter and then through the solution in the cuvette. Absorbance of solution is then recorded. 3. The filter is chosen to ensure that the light which passes through the solution shows the greatest absorbance (usually the complementary colour). NB => some colorimeters have two cuvettes - one is blank (or contains water) as is used as a reference. 4. Process is repeated using a range of known concentrations and a calibration graph is plotted of absorbance (y) against concentration (x). 5. Solution of unknown concentration then placed in cuvette and absorbance is measured. The calibration curve is then used to calculate its concentration.
(Other 3) Outline how to use a colorimeter to measure the absorbance of a solution.
Colorimetry can be used to monitor reactions such as when measuring the rate of reaction - only small quantities and is a fast and accurate method of calculating the concentration of a transition metal solution.
(Other 3) Why would we use colorimetry?
Benzene is more stable than cyclohexene by a certain enthalpy change
152
acidified potassium dichromate VI goes from orange to green
1st or 2nd degree alcohol and aldehyde
M(OH)2(H2O)4
2+ ion general formula
CoCO3 = mauve ppt [Co(NH3)6]2+ = straw/yellow [Co(NH3)6]3+ = yellow
2+ ion summary
M(OH)3(H2O)3
3+ ion general formula
[Fe(H2O)6]3+ = violet but turns brown upon hydrolysis
3+ ion summary
- positive ions are accelerated by an electric field to a constant KE - all have same KE velocity depends on mass, lighter = faster, heavier = slower
Acceleration: What happens?
A measurement result is considered accurate if it is judged to be close to the true value.
Accuracy.
Ester + HCl
Acyl Chloride + Alcohol =
Amide + HCl
Acyl Chloride + Amine =
Nucleophilic Addition Elimination NH3
Acyl Chloride to Amide
Nucleophilic Addition Elimination Alcohol
Acyl Chloride to Ester
Nucleophilic Addition Elimination Amine
Acyl Chloride to N-Substituted Amide
[Al(OH)4]- Colourless solution
Al hydroxide plus NaOH forms? What colour is this and what state is it in?
-OH on the end next to carbon
Alcohol functional group
suffix - al prefix - formyl-
Alcohol suffix/prefix
suffix - ol prefix - hydroxy-
Alcohol suffix/prefix
Oxidation Primary Alcohol H2SO4 K2Cr2O7 Distillation
Alcohol to Aldehyde
Elimination H3PO4 Heat
Alcohol to Alkene
Oxidation H2SO4 K2Cr2O7 Reflux
Alcohol to Carboxylic Acid
Esterification Carboxylic Acid Conc. H2SO4 Or Acyl Chloride/Acid Anhydride
Alcohol to Ester
Oxidation H2SO4 K2Cr2O7 Secondary Alcohol
Alcohol to Ketone
C=O and C-H same carbon
Aldehyde functional group
Reduction NaBH4 Primary Alcohol Formed
Aldehyde to Alcohol
Oxidation H2SO4 K2CrO7 Reflux
Aldehyde to Carboxylic Acid
carboxylic acid
Aldehyes are oxidise into what (or primary alcohols further oxidises into what)
-ane
Alkane suffix/prefix?
Free Radical Substitution Halogen eg Cl2 UV Light
Alkane to Halogenoalkane
-ene
Alkene suffic
Hydration Steam Dilute H2SO4 Catalyst Reflux 60-70 atm Pressure 300 Degrees Temperature
Alkene to Alcohol
Hydrogenation H2 Ni catalyst Heat
Alkene to Alkane
Electrophilic Addition Conc. H2SO4
Alkene to Alkyl hydrogensulfate
Electrophilic Addition Br2, or HBr
Alkene to Halogenoalkane
Hydrolysis Warm Dilute
Alkyl Hydrogensulfate to Alcohol
Al(H2O)3(OH)3(s) +OH-(aq) -> [Al(OH)4]-(aq)+3H2O(l)
Aluminium hydroxide with a base
Al(H2O)3(OH)3(s) +3H+(aq) -> [Al(H2O)6]3+(aq)
Aluminium hydroxide with an acid
Al2O3 + 6H+ -> 2Al3+ + 3H2O
Aluminium oxide acting as a base ionically
Al2O3 (s)+ 3H2SO4 (aq) -> Al2(SO4)3 (aq) + 3H2O (l)
Aluminium oxide acting as a base with H2SO4
Al2O3 + 6HCl -> 2AlCl3 + 3H2O
Aluminium oxide acting as a base with HCl
Al2O3 (s)+ 2OH- (aq) + 3H2O (l) -> 2Al(OH)4- (aq)
Aluminium oxide acting as an acid ionically
Al2O3 (s)+ 2NaOH (aq) + 3H2O (l) -> 2NaAl(OH)4 (aq)
Aluminium oxide acting as an acid with NaOH
Nucleophilic Addition Elimination Acyl Chloride
Amine to N-Substituted Amide
These are values in a set of results which are judged not to be part of the variation caused by random uncertainty.
Anomalies.
Yes
Are the physical properties of aldehydes and ketones similar?
Racemate....equal quantity of both Optical isomers
Asymmetrical Carbonyls will react with Nucleophiles to give products......Why is the product not optically active?
Only one Optical isomer is produced
Asymmetrical alcohols will undergo Nucleophilic Substitution........Why is the product not optically active?
salt and water
Basic oxides react with acids to make?
An unsaturated carbon ring, with delocalised electrons in the centre, which cannot undergo addition reactions
Benzene
Marking a scale on a measuring instrument. This involves establishing the relationship between indications of a measuring instrument and standard or reference quantity values, which must be applied.
Calibration.
Not Tertiary
Can all Alcohols be Oxidized to a Carbonyl?
Reduction NaBH4
Carboxylic Acid to Aldehyde
Esterification Alcohol conc. H2SO4
Carboxylic Acid to Ester
Ester and Water
Carboxylic acid + Alcohol =
Amide + Water
Carboxylic acid + Amine =
-oic acid
Carboxylic acid suffix
C=O and C-OH on the same Carbon
Carboxylic acids functional group
Categoric variables have values that are labels eg names of plants or types of material or reading at week 1, reading at week 2 etc.
Categoric variables.
The form of amine within dyestuffs. Also known as quaternary ammonium salts
Cationic Surfactants
polyesters and polyamides can be broken down by hydrolysis and are biodegradable
Chemical reactivity of condensation polymers?
warm with silver nitrate, slow formation of white ppt of AgCl
Chloroalkane
(Straw/yellow -> yellow) Change in oxidation state
Co as the metal ion draw the equation to show how a straw/yellow liquid changes into a yellow liquid. In this equation what is causing the colour change?
Fe(III) - brown ppt Al - white ppt
Colour of 3+ ions
Continuous variables can have values (called a quantity) that can be given a magnitude either by counting (as in the case of the number of shrimp) or by measurement (eg light intensity, flow rate etc).
Continuous variables.
C=O is stronger and does not undergo addition reactions easily
Contrast between C=O and C=C in alkenes?
A control variable is one which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored.
Control variables.
[Cr(OH)6]3- Green Solution
Cr hydroxide plus NaOH forms? What colour is this and what state is it in?
Information, either qualitative or quantitative, that has been collected.
Data.
The changing solubility of amines as the chain length increases (primary amines)
Decreases
Electron pair acceptor
Define Lewis acid
Electron pair donator
Define Lewis base
- weighted average mass of an atom of an element and all its isotopes on a scale where an atom of carbon 12 is 12
Define RAM
average mass of an atom of a molecule on a scale where an atom of carbon 12 is 12
Define Relative molecular mass
Lone proton donor
Define bronsted lowry acid
- weighted average mass of an atom of an isotope of an element on a scale where an atom of carbon 12 is 12
Define relative isotopic mass
Electron pair acceptor
Define the term Lewis acid
The dependent variable is the variable of which the value is measured for each and every change in the independent variable.
Dependent variables.
A rigid plastic
Describe PVC
Double covalent bond Planar bond Area of high electron density
Describe the C=C double bond
e-'s move from area of high electron density to delta + H e-'s in H-Br bond move to delta - Br Carbocation forms Lone pair of e-'s on :Br- attracted to C+ HBr has been added across the double bond
Describe the mechanism by which HBr is added to ethene
Bromine added to water to form bromine water Bromine water mixed with organic sample If colour changes from orange to colourless (without gas released) there are C=C bonds present If remains orange, there are no C=C bonds
Describe the test for unsaturation
Other processes such as fuel for machinery and transport
Despite the equations suggesting so, why is ethanol not a true carbon-neutral fuel?
- ions reach detector and generate a current which is fed into a computer for analysis - current produced by electrons transferring from detector to positive ions - size of current proportional to abundance of species
Detection:
show all the covalent bonds and atoms present in a molecule
Displayed formula?
Saves raw materials, nearly all polymers are formed from compounds sourced. Saves precious resources, polymers need collecting and sorting which is expensive. They can only be recycles into the same time and thermoplastic polmyers can be melted down and reshapes
Disposing polymers by recycling
Rubbish is burnt and energy produced is used to generate electricity. Some toxins can be released on incineration, many incinerators can burn more efficiently removing most toxins, greenhouse gases will still be emitted though, less rubbish is produced
Disposing polymers in INcineration
- most common method of disposla of waste in the UK, many are now reaching capacity. Expensive, most polymers (polyalkenes) are non biodegradable and take many years to break down. Could use more biodegradable plastics
Disposing polymers in landfill
Yes limited association with water molecules
Do Carbonyls dissolve in water?
Higher
Do Carbonyls have a higher or lower boiling point when compared to a corresponding Alkane?
Lower
Do Carbonyls have a lower or higher boiling point when compared to a corresponding Alcohol?
Not necessarily, just a lone pair of electrons
Do nucleophiles have to have a negative charge?
Green solution. Green solution then oxidised to yellow solution.
Draw an equation to show the reaction of Chromium with excess NaOH and then H2O2. State the colours of the complexes formed.
2+ NH3 pale brown / straw -> 3+ yellow
Draw diagram of reactions of Co(II) with OH-/NH3, 2 different oxidations (O2) and Excess NH3 and state the colours
Blue = donor sites
Draw the EDTA4- anion
1) Push the equilibrium to the dichromate (Orange solution) 2) Remove the H+ ions and push the equilibrium to the chromate ions
Draw the acid base equilibrium between CrO42- and Cr2O72-. 1) What will happen when acid is added 2) What will happen when alkali is added
Pink solution -> Blue solution
Draw the equation for the formation of the Co Cl Complex. State the colour changes.
Blue solution -> Yellow-green solution
Draw the equation for the formation of the Cu Cl complex. State the colour changes.
Pink solution -> Mauve ppt
Draw the equation for the reaction of Co aqueous complex with carbonate. Write the colour changes.
Blue solution -> Green ppt
Draw the equation for the reaction of Cu aqueous complex with carbonate. Write the colour changes.
Green solution-> Green ppt
Draw the equation for the reaction of Fe (II) aqueous complex with carbonate. Write the colour changes.
(Pink -> straw /yellow) Change in ligand
Draw the equation in which Co is the central metal ion and the complex changes from a pink solution to a yellow brown solution. In this equation what is causing the colour change?
Blue ppt -> Straw/yellow solution
Draw the equation of the neutral complex Co undergoing ligand substitution with NH3. Write colour change.
Green ppt -> Purple solution
Draw the equation of the neutral complex of Cr undergoing ligand substitution with NH3. Write colour change.
Blue ppt -> Deep blue solution
Draw the equation of the neutral complex of Cu undergoing ligand substitution with NH3. Write colour change.
Change in co-ordination number and ligand
Draw the equation that forms a blue solution from a pink solution Co as the central metal ion. In this equation what is causing the colour change? What is the colour change?
[Al(H2O)6]3+ + 3NH3 -> [Al(H2O)3(OH)3] + 3NH4+ White ppt
Draw the equation when limited NH3 reacts with Al. Colour of precipitate.
Blue ppt
Draw the equation when limited NH3 reacts with Co. Colour of precipitate formed.
[Cr(H2O)6]3+ + 3NH3 -> [Cr(H2O)3(OH)3) + 3NH4+ Green ppt
Draw the equation when limited NH3 reacts with Cr. Colour of precipitate
[Cu(H2O)6]2+ + 2NH3 -> [Cu(H2O)4(OH)2] + 2NH4+ Blue ppt
Draw the equation when limited NH3 reacts with Cu. Colour of precipitate formed.
[Fe(H2O)6]2+ + 2NH3 -> [Fe(H2O)4(OH)2] + 2NH4+ Green ppt
Draw the equation when limited NH3 reacts with Fe (II). Colour of precipitate formed.
Brown ppt
Draw the equation when limited NH3 reacts with Fe (III). Colour of precipitate.
[Al(H2O)6]3+ + 3OH- -> [Al(H2O)3(OH)3] + 3H2O White ppt
Draw the equation when limited OH- reacts with Al. Colour of precipitate formed.
[Co(H2O)6]2+ + 2OH- -> [Co(H2O)4(OH)2] + 2H2O Blue ppt
Draw the equation when limited OH- reacts with Co. Colour of precipitate formed.
Green ppt
Draw the equation when limited OH- reacts with Cr. Colour of precipitate formed.
Blue ppt
Draw the equation when limited OH- reacts with Cu. Colour of precipitate formed.
[Fe(H2O)6]2+ + 2OH- -> [Fe(H2O)4(OH)2] + 2H2O Green ppt
Draw the equation when limited OH- reacts with Fe (II). Colour of precipitate formed.
[Fe(H2O)6]3+ +3OH- -> [Fe(H2O)3(OH)3] + 3H2O Brown ppt
Draw the equation when limited OH- reacts with Fe (III) Colour of precipitate formed.
Blue precipitate to brown precipitate
Draw the full equation for the reaction of Co(H2O)4(OH)2 and an oxidising agent. What are the colour changes?
Yellow
Draw the overall equation for the reaction between the green solution formed when chromium reacts with something and an oxidising agent. What colour is the product formed?
Al(H2O)3(OH)3 White ppt
Draw the precipitate formed when limited OH-/NH3 react with Al. What colour is this?
Blue ppt
Draw the precipitate formed when limited OH-/NH3 react with Co. What colour is this?
Green ppt
Draw the precipitate formed when limited OH-/NH3 react with Cr. What colour is this?
Blue ppt
Draw the precipitate formed when limited OH-/NH3 react with Cu . What colour is this?
Fe(H2O)3(OH)3 Brown ppt
Draw the precipitate formed when limited OH-/NH3 react with Fe (III) What colour is this?
Fe(H2O)4(OH)2 Green ppt
Draw the precipitate formed when limited OH-/NH3 react with Fe(II). What colour is this?
...
Draw the product formed after the reaction between the amino acid serine and CH3Br
(Zwitterion) - Ionic
Draw the structure of aminoethanoic acid in solid form, and state the type of bonding within this solid?
Main use for amines
Dyestuffs
- Bohr, predicted atoms and ions with noble gas electron arrangements should be stable
Early model of the atom
increases ROR without getting used up, providing an alternative route with a lower Ea
Effect of catalysts?
- a vaporised sample is injected at low pressure - electron gun fires high energy electrons at the sample - knows out outer electron - forms positive ions with different charges E.g. Ti -> Ti+ + e-
Electron Impact?
- orbitals - 1/1840 - -1
Electron: location, relative mass, relative charge
- +ve ion - electrons are LOST - -ve ion - electrons are GAINED
Electronic structure for Ions?
The mechanism to add a different R group to a benzene ring. This is the main type of reaction that occurs as the benzene ring is an area of high electron density so requires like charge displacement. The ring is also very stable so the reaction has to be of a high energy to destabilise the ring
Electrophilic Substitution
- sample dissolved in volatile polar solvent - injected through fine hyperdermic needle giving a fine mist or aerosol - tip of needle has high voltage - tip of needle sample molecule M gains a proton H+ from solvent forming MH+ - M(g) + H+ -> MH+ (g) - solvent evaporates away while MH+ ions move towards negative pole
Electrospray?
shows the simplest whole number ratio of atoms of each element in the compound
Empirical formula?
t = d.rtm/2KE
Equation combining KE and speed
v = rt2KE/m
Equation for KE to find v?
- KE = 1/2mv^2
Equation for KE?
Distance = speed x time
Equation for speed distance and time?
2[Al (H2O)6]3+(aq) + 3CO32-(aq) -> 2Al(OH)3(H2O)3(s) +3CO2 + 3H2O(l)
Equation of Al3+
2[Fe(H2O)6]3+(aq) + 3CO32-(aq) -> 2Fe(OH)3(H2O)3(s) +3CO2 + 3H2O(l)
Equation of Fe3+
Na2O(s) + H2O (l) -> 2Na+ (aq) + 2OH- (aq)
Equation when sodium oxide reacts with water?
2Na(s)+2H2O(l) -> NaOH(aq) + H2(g)
Equation when sodium reacts with cold water?
SO2 + H2O -> H+ + HSO3- SO3 + H2O -> H+ + HSO4-
Equations of SO2 and SO3 to show formation of ions in solution?
(uncertainty in measurement) x100 / (quantity measured). Choosing a suitable scale minimises % error: - Low titre value = high % error in burette. - Low mass = high % error in balance. If two measurements are used to generate a piece of data than the uncertainty value is doubled.
Errors - Apparatus uncertainty: - % uncertainty = - Comment on necessity to choose a suitable scale. - If two measurements are used...
= (actual value - calculated value) x100 / (actual value). If experimental error < apparatus error, then the result is relatively accurate. If experimental error > apparatus error, result is inaccurate.
Errors - Experimental Errors: - % Experimental Error = - How can we see if the result is accurate/inaccurate?
C=O C-O same carbon
Ester functional group
-yl-oate
Ester suffix?
electronegativity difference being less big or alternatively by the small aluminium ion with a high charge being able to get close to the oxide ion and distorting the oxide charge cloud
Explain Al2O3
Fats/Oils react with a base (such as sodium/potassium hydroxide). Products = Glycerol + soap (long chain fatty acid + sodium ion)
Explain how a fat/oil can be hydrolyzed + the products formed
Dicarboxylic acid reacts with diamine. Water molecule is released and Nitrogen bonds with carbon to form the amide group.
Explain how a polyamide is made (draw diagram)
The nitrogen atoms on guanine have lone pairs of electrons which form dative covalent bonds with the platinum. They displace chloride ions because they are better ligands.
Explain how cisplatin bonding to DNA is an example of a ligand substitution reaction
The have empty d-orbitals of low energy which can accept electron pairs
Explain how transition metals can form complex ions
The splitting of NMR peaks as the applied magnetic field on any H atoms is affected by the magnetic field of hydrogen atoms on neighbouring carbon atoms
Explain spin-spin coupling
1) Draw line in pencil near the bottom of the TLC plate (the baseline) and put small drop of each mixture to be separated on the line 2) Allow spots to dry and place the plate in a beaker with a small volume of solvent (mobile phase) below the drawn line so it doesn't dissolve the samples away 3) Solvent moves up plate and as it moves the solvent will carry substances in the mixture with it - some chemicals will be carried faster than others and so travel further up the plate 4) Wait till solvent has reached almost the top then remove from beaker before it's evaporated and use a pencil to mark how far the solvent traveled up the plate (solvent front) 5)
Explain the process of thin-layer chromatography (TLC)
• A glass tube is filled with the stationary phase usually silica or alumina in powder form to increase the surface area. • A filter or plug is used to retain the solid in the tube. Solvent is added to cover all the powder. • The mixture to be analysed is dissolved in a minimum of a solvent and added to the column. • A solvent or mixture of solvents is then run through the column. • The time for each component in the mixture to reach the end of the column is recorded (retention time)
Explain the steps of column chromatography
Major product formed via carbocation which has most alkyl groups bonded to it Minor product is formed via carbocation which has least alkyl groups bonded to it Tertiary carbocation more stable than secondary more stable that primary
Explain when major and minor products form in electrophilic addition to unsymmetrical alkenes
Tertiary carbocation has more alkyl groups attached Positive inductive effect Reduce + charge on carbon More stable Remains in reaction mixture for longer so more likely to react with electrophile
Explain why a tertiary carbocation forms the major product and a secondary/primary carbocation forms the minor product
- attraction of the nucleus - more protons stronger attraction - distance of electrons, bigger atom, further electrons so weaker attraction - shielding of attraction - outer shell repelled by electrons in inner shells, weaker attraction
Factors that affect Ionisation energy?
A fair test is one in which only the independent variable has been allowed to affect the dependent variable.
Fair test.
Oxygen to be transported in the blood,
Fe(II) in haemoglobin enables what?
- show a gradual change in physical properties - each member differs by CH2 from the last - same chemical properties
Features of organic compounds?
CH3CHO + 2Cu2+ + 2H2O -> CH3COOH + Cu2O + 4H+
Fehlings solution with an aldehyde
- positive ions with smaller m/z values will have same KE as those with larger m/z values but will move faster - ions distinguished by different flight times, no electric field so drift
Flight Tube/ion drift: What happens?
AlCl3
Formula for aluminium chloride
The substitution mechanism catalysed by AlCl3. Which reforms at the end of the reaction
Friedel-Crafts Acylation
benzene-1,4-dicarboxylic acid benzene-1,6-diamine
From which molecules is Kevlar formed?
3CH3CHO + Cr2O72- + 8H+ -> 3 CH3CO2H + 4H2O + 2Cr3+
Full equation for oxidation
Colour change from straw yellow to yellow
Full equation for the oxidation of [Co(NH3)6]2+ - state the colours
compounds with the same molecular formula but with atoms arranged to give different functional groups
Functional group isomers?
algebraic formula for a homologous series
General formula?
They have high melting/boiling points
Give a physical properties of polymers
Benzene - 1,4 - dicarboxylic acid + Ethane - 1,2, - diol to form Terylene
Give an example of how a polyester is synthesised
The copper complex ion has changed from having unidentate ligands to a multidentate ligand. In this reaction there is an increase in entropy as there are more moles of products that reactants (from 2 to 7), creating more disorder The enthalpy change is small as there are similar numbers of bonds in both complexes, free energy change will be negative as delta S is positive and delta H is small
Give an example of the chelate effect
CCl4 (tetrachloromethane) which has no hydrogen atoms Other solvents contain deuterium which is an isotope of hydrogen but produces peaks at a different range to Hydrogen
Give examples of solvents used in 1H NMR and why they are used
1) Nylon 6,6, is made from hexanedioic acid and 1,6 - diaminohexane ... 2) Kevlar - Benzene - 1,4 - dicarboxylic acid and 1,4-diaminobenzene
Give examples of two polyamides and how they are synthesised (draw diagrams)
V2O5 in the contact process Cr2O3 in the manufacture of methanol from carbon dioxide and hydrogen Fe in the Haber process
Give three examples of heterogenous catalysts
Fe2+ in the reaction between iodide and persulphate ions Autocatalysis by Mn2+ in titrations of C2O42- with MnO4-
Give two examples of homogenous catalysts
Polyamides Polyesters
Give two types of condensation polymers
halogen on a carbon
Halogenoalkane functional group?
Nucleophilic Substitution Aqueous NaOH Heat Reflux
Halogenoalkane to Alcohol
Elimination Ethanolic NaOH Reflux
Halogenoalkane to Alkene
Nucleophilic Substitution Excess NH3 Warm Ethanolic
Halogenoalkane to Amine
Nucleophilic Substitution Ethanolic KCN Warm Reflux
Halogenoalkane to Nitrile
families of organic compounds with the same functional group and same general formula
Homologous series?
Using hydrogen perodicde
How are chromium and cobalt compounds oxidised?
Carboxylic acid reacts with alcohol to give ester + water. A strong acid catalyst such as HCl (concentrated) is required (this is called esterification). Conditions = heated under reflux.
How are esters formed?
The order of reaction of a reactant = how many moles of that reactant are in the rate determining step
How are number of moles in the rate-determining step and the order of reactions of a reactant linked?
Dicarboxyl + diol
How are polyesters made?
Because the two steps in the mechanism can occur in any order
How can Fe3+ ions also act as a catalyst for the reaction between I- and S2O82-?
- Mass Spec's in planetary space probes - elements on other planets can have different composition of isotopes
How can elements on other planets be identified?
- can determine all the isotopes present in a sample of an elemets
How can mass spectrometry identify elements?
With the choice of a suitable indicator [Cu(H2O)6]2+ + EDTA4- -> [Cu(EDTA)]2- + 6H2O
How can the formation of the stable EDTA complex with metal ions be used as a quantitative titration?
Boiling it with water
How can the product of the electrophilic addition of Sulfuric acid to an alkene be converted to an alcohol?
by the presence of polar bonds which can attract attacking species such as nucleophiles and acids
How can this reactivity be explained?
By removing samples at set times and titrating to work out the concentration of MnO4- It could also be done by use of a spectrometer measuring the intensity of the purple colour
How can you follow the reaction rate of the reaction between C2O42- and MnO4-?
Boil it with 6moldm-3 of hydrochloric acid for 24 hours
How can you hydrolyse a protein or polypeptide?
Sometimes a compound containing a complex may have Cl- ions acting as ligands inside the complex and Cl- ions outside the complex that are attracted ionically to it. If silver nitrate is added to such a compound it will only form the silver chloride precipitate with the free chloride ions outside the complex
How can you use silver nitrate to work out formulae for chloride containing complexes?
Work out gradient
How can you work out the rate of reaction using a concentration vs time graph?
because of the greater polarising power of the 3+ ion due to its higher charge density
How come MCO3 is formed with 2+ ions but M2(CO3)3 is not formed with 3+ ions?
due to restricted rotation around the C=C bond
How do E-Z isomers exist
- in order of increasing energy - BUT 3d is higher in energy than 4s so fills first
How do atoms fill up subshells?
Form a salt + Carbon dioxide + Water
How do carboxylic acids react with carbonates?
By impurities and consequently have reduced efficiency
How do catalysts become poisoned?
By providing an alternative route with a lower activation energy
How do catalysts increase reaction rates without getting used up?
Changes in: Oxidation state Co-ordination number Ligand
How do colour changes arise?
Presence of strong acid catalyst. Forms carboxylic acid + alcohol (reverse of above reaction)
How do esters react with water?
Form a MCO3 ppt
How do the 2+ ions react with carbonate solution?
Form a M(OH)3(H2O)3 ppt and CO2 gas is evolved
How do the 3+ ions react with carbonate solution?
From an incomplete d sub-level in atoms or ions
How do the characteristics of transition metals arise?
Stronger
How do the intermolecular forces between condensation polymer chains compare to those between addition polymer chains?
The OH group of a phosphate on one nucleotide reacts with an OH group on a sugar on another nucleotide to eliminate a water molecule
How do two nucleotides link?
Distance travelled by spot/distance travelled by solvent
How do we calculate the Rf value?
Add Sodium Hydrogen Carbonate (NaHCO3) - effervescence = carboxylic acid present
How do we distinguish between a carboxylic acid and an ester?
Many TLC plates have fluorescent dye added to silica or alumina layer that glows when UV light is shone Expose chromatogram to iodine vapor (leaving the plate in a sealed jar with iodine crystals) - iodine vapour is a locating agent as it sticks to the chemicals on the plate and they'll show up as purple spots
How do we make colourless chemicals separated from TLC visible?
The highest atomic number closest to the double bond has the highest priority If two groups have e.g. Only carbon and hydrogen, then the one with the most carbon atoms is assigned the highest priority
How do you assign the highest priority of groups in E-Z isomerism?
mixing aq ammonia and silver nitrate forming complex ion of [Ag(NH3)2]+
How do you form tollens reagent
Draw a tangent to the line where time =0
How do you work out the initial rate of reaction using a concentration-time graph?
Magnetic field is applied to a sample which is surrounded by a source of radio waves and radio receiver. This generates an energy change in the nuclei of atoms in the sample that can be detected.
How does NMR work?
Think dative covalent bonding and hydrogen bonding
How does cisplatin join to DNA?
Through preventing the replication of healthy cells by bonding onto healthy DNA which may lead to unwanted side effects like hair loss
How does cisplatin lead to side effects?
It bonds to strands of DNA and distorts their shape to prevent replication of the cells. The molecule bonds to nitrogen atoms on two adjacent guanine bases
How does cisplatin work?
1) [Al(H2O)6]3+ (aq) + OH- (aq) -> [Al(H2O)5(OH)]2+ (aq) + H2O (l) 2) [Al(H2O)5(OH)]2+ (aq) + OH- (aq) [Al(H2O)4(OH)2]+ (aq) + H2O (l)
How does deprotonation occur by removing one proton at a time with Al3+ and OH-
certain groups in a molecule absorb infra red radiation
How does it work?
The bigger k is, the faster the rate of reaction
How does k affect the rate of reaction?
They may need to be replaced e.g. poisoning by sulphur in the haber process and by lead in catalytic converters in cars
How does poisoning have a cost implication?
It can form complexes and can show catalytic behaviour
How does silver behave like other transition metals?
The electronic transitions from the ground state to excited states (between different d orbitals)
How does the colour arise in transition metals?
When molecule moves close area of high electron density (C=C double bond) It becomes polarised Electrons in C=C repel electrons in neutral molecule Forms polar electrophile
How does the electrophile form in non-polar molecules such as Br2?
A small amount of sodium thiosulphate and starch are added to an excess of hydrogen peroxide and iodide ions in acid solution
How does the iodine clock reaction occur?
To begin with all the iodine from the first reaction is used up in the second reaction, but once all the sodium thiosulphate is used up, any iodine produced stays in the solution so the starch indicator will turn blue black - this is the end of the clock reaction
How does the iodine clock reaction work?
As both of the individual stages in the catalysed mechanism involve collision between positive and negative ions and will have lower activation energies
How does using Fe2+ in the reaction between I- and S2O82- reduce the activation energy?
Br2 gas bubbles through alkene Absence of light Temperatures below room temp
How is Br2 reacted with alkenes?
protected from corrosion in moist air by a thin layer of aluminium oxide. The high lattice strength of aluminium oxide and its insolubility in water make this layer impermeable to air and water
How is aluminium metal stored?
Water removed as one OH group and one H removed from two carboxylic acids.
How is an acid anhydride formed?
Vegetable oils react with methanol (strong alkaline catalyst present) to give glycerol + mixture of methyl esters of long chain carboxylic acids (known as biodiesel)
How is biodiesal formed?
The yeast produces ethanol during anaerobic respiration, using glucose as its food
How is ethanol made using yeast?
Distillation, as the boiling point of ethanol (78°C) is below that of water
How is ethanol removed from the aqueous mixture produced after fermentation?
Fermentation using yeast
How is over 90% of ethanol made?
It doesn't form coloured compounds or have variable oxidation states
How is silver unlike the other transition metals?
Six bonds per ligand
How many coordinate bonds an EDTA4- form?
10
How many electrons does d hold?
14
How many electrons does f hold?
6
How many electrons does p hold?
2
How many electrons does s hold?
1
How many molecules of water are eliminated on the formation of 1 amide or ester group?
Balance as if under acidic conditions and then add OH- ions to both sides to convert to alkaline
How to create an alkaline half equation
- count how many points before each big jump to find how many electrons in each shell, number of points = electrons in each shell
How to find electronic structure from graph?
- how many electrons are removed before the first big jump to find group number e.g. 1 electron removed = group 1
How to find group from graph?
melt the solids and show they conduct electricity?
How to prove the compounds contain ions experimentally?
Track colour change using a colorimeter that measures the absorbance of light of a particular wavelength
How would you conduct an experiment when there is a colour change?
Us the ideal gas equation to work out the number of moles, then use the molar ratio to work out the concentration
How would you draw a concentration-time graph for an experiment where gas is the product?
Collect gas in a syringe and record how much there is at regular time intervals
How would you measure an experiment where the product is a gas?
Measure the mass of the system at regular intervals using a balance
How would you measure an experiment where there is a change in mass?
Measure pH at regular intervals
How would you measure an experiment where there is a change in pH?
Identify the longest carbon chain Identify the position of the carbon carbon double bond Identify any side chains
How would you name an alkene given its displayed formula?
A proposal intended to explain certain facts or observations.
Hypothesis.
prefix of hydroxy
If compound has -OH group in addition to other functional group then how do you name OH?
The aqueous [Cu(H2O)6]2+ complex not [CuCl4]2- complex
If solid copper (or any other metal) chloride is dissolved in water what is formed?
do not remove the -e from the stem alkane name
If suffix starts with a consonant or there are two or more of a functional group
remove the -e from the stem alkane name
If suffix starts with a vowel?
poly(2-chloropropene)
If the monomer is 2-chloropropene, what is the polymer?
A lewis base donating an electron pair
In ligand substitution reactions what is NH3 acting as?
Green due to hydrolysis reactions
In solution what colour does Cr(III) often appear and why?
Yellow/brown due to hydrolysis reactions
In solution what colour does Fe(III) often appear and why?
due to hydrolysis reactions
In solution why does Fe(III) appear yellow/brown
- different spins of electrons in orbital
In spin diagrams what do arrows in opposite directions represent?
Polyamides have hydrogen bonding between chains Polyalkenes have van der Waals' forces between chains Hydrogen bonding is stronger
In terms of intermolecular forces, explain why polyamides can be used to make fibres for clothing and polyalkenes can't
The metal ion as it is accepting a pair of electrons in the dative covalent bond
In the formation of a complex ion what is the lewis acid?
The ligand as it is donating a pair of electrons in the dative covalent bond
In the formation of a complex ion what is the lewis base?
Bronsted-Lowry bases accepting a proton
In this what are the NH3 and OH- acting as
Cu(OH)2(H2O)4(s) + 4NH3 (aq) -> [Cu(NH3)4(H2O)2]2+ (aq) + 2H2O (l) + 2OH- (aq)
Incomplete Substitution of Cu
more particles per unit volume so the particles collide with a greater frequency and there will be a higher frequency of effective collisions
Increasing conc and pressure?
more frequent successful collisions so ROR increases
Increasing surface area?
particles have more energy, more collisions and with energy greater than Ea
Increasing temp?
The independent variable is the variable for which values are changed or selected by the investigator.
Independent variables.
The power of the lone pair to become more available when the N is bonded to more R groups
Inductive Effect
hydrogen bonding between the oxygen in C=O groups and the H in N=H groups in the different chains in addition to the VDW forces
Intermolecular bonding in polyamides
they have permanent dipole forces between the C=O groups in the different chains in addition to the VDW forces between the chains
Intermolecular bonding in polyesters
The quantity between readings.
Intervals.
MgO (s) + 2 H+ (aq) -> Mg2+ (aq) + H2O (l)
Ionic MgO and Acid?
Na2O (s) + 2H+ (aq) -> 2Na+ (aq) + H2O (l)
Ionic Na2O and acid?
Negatively charged ion
Is it easier to remove an electron from a negatively charged ion or a positively charged ion?
C=O on central carbon
Ketone functional group
suffix -one prefix -oxo-
Ketone suffix/prefix
Reduction NaBH4 Secondary Alcohol
Ketone to Alcohol
Nucleophilic Addition HCN
Ketone to Hydroxynitrile
Knowledge and understanding of the production and properties of polymers has developed over time
Knowledge and understanding of the production and properties of polymers has developed over time
electron pair donator
Lewis Base
electron pair acceptor
Lewis acid
The same hydroxide precipitates
Limited and OH- and NH3 form?
The part of the amine that is most reactive
Lone Pair
ionisation acceleration ion drift ion detection data analysis
Mass Spec: Order
The difference between a measured value and the true value.
Measurement error.
- no fragmentation - one peak will equal mass of MH+ ion so subtract 1 to get Mr
Measuring Mr of . a molecule using electrospray
- break up and gives series of peaks - peak with largest m/z due to complete molecule and will be the Mr of the molecule - called the molecular ion
Measuring Mr of a molecule electron impact?
1) Add an appropriate ligand to INTENSIFY colour 2) Make up solutions of known concentration 3) Measure absorption or transmission 4) Plot graph of results or calibration curve 5) Measure absorption of unknown and compare
Method for spectrometry
MgO (s) + 2 HCl (aq)MgCl2 (aq) + H2O (l)
MgO and HCl
The formula which shows the actual number of each type of atom
Molecular formula?
are polyesters and polyamides
Most common types of condensation polymers?
Na2O (s) + H2SO4 (aq) -> Na2SO4 (aq) + H2O (l)
Na2O and H2SO4
Na2O (s) + 2 HCl (aq) -> 2NaCl (aq) + H2O (l)
Na2O and HCl
Cl-
Name a larger ligand
EDTA4-
Name a multidentate ligand
Methanal (a named aldehyde)
Name a reagent or mixture of reagents necessary to convert [Ag(NH3)2]+ -> Ag
H2O2 + NaOH
Name a reagent or mixture of reagents necessary to convert [Cr(H2O)6]3+ -> CrO4^2-
Fe2+ with MnO4-
Name another redox titration using Fe2+
M - Fe = green, Co = pink, Cu = blue
Name three M2+ ions, their colours and draw their general aqueous solution formula
M - Al = colourless, Cr = ruby (GREEN!) , Fe = violet (YELLOW/BROWN) (ruby and violet only really seen in solid hydrated salts that contain these complexes)
Name three M3+ ions, their colours and draw their general aqueous solution formula
Zn2+ Cu+ Sc3+
Name three ions that form compounds without colour
H2O NH3 Cl-
Name three unidentate ligands
NH2CH2CH2NH2 Ethandioate ion (C2O42-)
Name two bidentate ligands
With hydrogen peroxide and with ethanedioate
Name two other useful manganate titrations
Hydrogen peroxide H2O2 and sometimes by standing in air
Name two oxidising agents that can be used to oxidise metal ions
NH3 and H20
Name two small ligands
- Nucleus - 1 - 0
Neutron: location, relative mass, relative charge
The substitution of NO2 for one of the H on a benzene rings
Nitration
Reduction LiAlH4 or NaBH4
Nitrile to Amine
A nominal variable is a type of categoric variable where there is no ordering of categories (eg red flowers, pink flowers, blue flowers)
Nominal variables.
1) Sweet smelling so used in perfumes/food colouring 2)Plasticiser - enables polymer chains to move more easily so they are more flexible.
Outline some of the uses of esters
...
Outline the nucleophillic addition-elimination mechanism
Fehlings, Acidified Potassium Dichromate, Tollens
Oxidising Agents to change Aldehydes to Carboxylics?
simple molecular, contain VDW + permanent dipoles
P4O10 and SO2
P4O10 + 6 Na2O -> 4Na3PO4
P4O10 and sodium oxide
P4O10 (s) + 6 H2O (l) -> 4 H3PO4(aq) pH 0 - v vigorous reaction
P4O10 and water and pH?
P4O10 (s) + 12 OH- (aq) -> 4PO4 3-(aq) + 6 H2O (l)
P4O10 plus hydroxide Ionic
P4O10 (s) + 12 NaOH (aq) -> 4Na3PO4(aq) + 6 H2O (l)
P4O10 reacting with NaOH base?
- Does it go through the origin? - Do not necessarily start at the origin if the line does not go through it. - When calculating the gradient, choose two points at opposite ends of the line of best fit.
Points to note with graphs?
Polyamides
Polyamides and polyesters - which has higher mp's?
Cu2+ (aq)+CO32-(aq) -> CuCO3(s)
Precipitation reaction ionic of Cu2+ in carbonate?
Fe2+ (aq)+CO32-(aq) -> FeCO3(s)
Precipitation reaction ionic of Fe2+ in carbonate?
[Cu(H2O)6]2++CO32- -> CuCO3+6H2O
Precipitation reaction non ionic of Cu2+ in carbonate?
[Fe(H2O)6]2++CO32- -> FeCO3+6H2O
Precipitation reaction non ionic of Fe2+ in carbonate?
Precise measurements are ones in which there is very little spread about the mean value. Precision depends only on the extent of random errors - it gives no indication of how close results are to the true value.
Precision.
aldehydes
Primary alcohols are oxidise into what?
Aldehyde, Carboxylic
Product of Oxiding a Primary Alcohol?
Not going to happen
Product of Oxidising a Ketone
Ketone
Product of Oxidising a Secondary Alcohol?
- nucleus - 1 - +1
Proton: location, relative mass, relative charge
primary< secondary < tertiary
Put the carbocations in order of stability
These cause readings to be spread about the true value, due to results varying in an unpredictable way from one measurement to the next. Random errors are present when any measurement is made, and cannot be corrected. The effect of random errors can be reduced by making more measurements and calculating a new mean
Random errors.
The maximum and minimum values of the independent or dependent variables.
Range.
heat gently and aldehydes are oxidises into a carboxylic acid and silver (I) ions are reduced to silver atoms so a silver mirror is formed, but no change with ketones
Reaction
heat gently, they are oxidises into a carboxylic acid and the copper (II) ions are reduced to copper (I) oxide, with Aldehyes will go from blue to red ppt but ketones don't react
Reaction for aldehydes
4Al + 3O2 (g) -> 2Al2O3 (s)
Reaction of Al with O
Mg(s) + H2O (g) -> MgO(s) +H2(g)
Reaction of Magnesium and water?
2Mg(s) + O2(g) -> 2MgO(s)
Reaction of Mg with O
4Na(s)+O2(g) -> 2Na2O (s)
Reaction of Na with O
4P + 5O2(g) -> P4O10 (s)
Reaction of P and O
S + O2 (g) -> SO2 (g)
Reaction of S and O
Si + O2 (g) -> SiO2 (s)
Reaction of Si and O
MgO(s) + H2O (l) -> Mg(OH)2 (s)
Reaction when MgO reacts with water?
hydrogen and nickel catalyst at high pressure
Reagent and conditions for catalytic hydrogenation?
NaCN/KCN and dilute H2SO4, room temp and pressure
Reagent when turning carbonyl to hydroxynitrile
NaBH4 or LiAlH4 in aqueous ethanol at room temp and pressure
Reagents and conditions for reduction of carbonyls
The process of forming nitriles from the cyanide ion and a halogenoalkane
Reduction
A measurement is repeatable if the original experimenter repeats the investigation using same method and equipment and obtains the same results
Repeatable.
A measurement is reproducible if the investigation is repeated by another person, or by using different equipment or techniques, and the same results are obtained.
Reproducible.
This is the smallest change in the quantity being measured (input) of a measuring instrument that gives a perceptible change in the reading.
Resolution.
pH9
Result when MgO reacts with water?
pH of 13 with a vigorous exothermic reaction
Result when Na2O reacts with water?
ln(k) = ln(Ae^(-Ea/RT) ln(k) = ln(A) - (Ea/RT) Ea/RT = ln(A) - ln(k)
Rewrite the Arrhenius equation
compare atomic number higher atomic number is given priority. If this is the same consider atoms at distance 2 from double bond
Rule when naming?
SO2 (g) + 2NaOH (aq) -> Na2SO3 (aq) + H2O (l)
SO2 and NaOH
SO2 (g) + H2O (l) -> H2SO3 (aq) pH 3
SO2 and water and pH?
SO2 (g) + 2OH- (aq) -> SO32- (aq) + H2O (l)
SO2 plus hydroxide ionic
SO3 (g) + 2NaOH(aq) -> Na2SO4 (aq) + H2O (l)
SO3 and NaOH
SO3 (g) + H2O (l) -> H2SO4 (aq) pH 0
SO3 and water and pH?
SO3 (g) + 2OH- (aq) -> SO42- (aq) + H2O (l)
SO3 plus hydroxide ionic
contain single carbon-carbon bonds only
Saturated?
ketones
Secondary alcohols are oxidised into what?
macromolecular - v high mp and bp
SiO2
2NaOH (l) + SiO2 (s) -> Na2SiO3 (aq) + H2O
SiO2 with concentrated NaOH?
shows the simplified organic formula, shown by removing hydrogen atoms from alkyl chains leaving just a carbon skeleton and associated functional groups
Skeletal formula?
A line graph, not necessarily on a grid, that shows the general shape of the relationship between two variables. It will not have any points plotted and although the axes should be labelled they may not be scaled.
Sketch graph.
The reagents required to convert a nitrobenzene to phenylamine
Sn/HCl
That the products cannot be released
Some metals have too strong of an adsorption e.g. W. What does this mean?
The reactants do not adsorb in high enough concentration
Some metals have too weak of an adsorption e.g. Ag. What does this mean?
same structural formula but different spatial arrangement of atoms
Stereoisomers?
shows the minimal detail that shows the arrangement of atoms in the molecule
Structural formula?
same molecular formula different structural formula
Structural isomer
When naming an amine, does the amine act as a prefix or suffix?
Suffix
These cause readings to differ from the true value by a consistent amount each time a measurement is made. Sources of systematic error can include the environment, methods of observation or instruments used. Systematic errors cannot be dealt with by simple repeats. If a systematic error is suspected, the data collection should be repeated using a different technique or a different set of equipment, and the results compared.
Systematic uncertainty.
Main use of a specific nitrated arene
TNT
do not oxidise
Tertiary alcohols and ketones?
sodium carbonate with effervescence of CO2
Test for Carboxylic Acid
Fehlings solution goes from blue to red ppt
Test for aldehyde
bromine water decolourises
Test for alkene
6 to 4
The addition of HCl to aqueous ions of Cu and Co lead to a change in co-ordination number form what to what?
Acids
The non metal, simple molecular and covalent oxides react with water to give what?
False Concentrated sulphuric acid is an electrophile
True or False Dilute sulphuric acid is an electrophile
True And at a good rate for HBr!
True or False The electrophilic addition reactions of HBr or conc H2SO4 and alkenes occur below room temperature
This is the value that would be obtained in an ideal measurement.
True value.
Addition and condensation
Two types of polymerisation?
- Electron impact and Electrospray onisation
Two ways of ionising?
The interval within which the true value can be expected to lie, with a given level of confidence or probability.
Uncertainty.
- KE = J - m = kg v = ms^-1
Units of KE, m and v
contains a C=C double bond
Unsaturated?
an acid catalyst and would only give an equilibrium mixture
Using carboxylic acid to make the ester or amide would need what?
Suitability of the investigative procedure to answer the question being asked. For example, an investigation to find out if the rate of a chemical reaction depended upon the concentration of one of the reactants would not be a valid procedure if the temperature of the reactants was not controlled
Vailidity.
A conclusion supported by valid data, obtained from an appropriate experimental design and based on sound reasoning.
Valid conclusion.
Fermentation or electrophilic addition of phosphoric acid and subsequent hydrolysis
What 2 industrial methods are used to convert alkenes into alcohols?
1,6-diaminohexane hexane-1,6-dioic acid
What 2 molecules react to form nylon-6,6 ?
1. Cl radical + CH4 ----> CH3 radical + HCL 2. Cl2 + CH3 radical ----> CH3Cl + Cl radical
What 2 reactions occur during the propagation step of the chlorination of methane?
1. CH3 radical + CH3 radical ----> C2H6 2. CH3 radical + Cl radical ----> CH3Cl 3. Cl radical + Cl radical ----> Cl2
What 3 reactions occur during the termination step of the chlorination of methane?
Photosynthesis, fermentation and combustion of ethanol, because overall 6 carbon dioxides go in and 6 carbon dioxides come out
What 3 reactions suggest that burning ethanol is carbon neutral and why?
Only use dilute sulphuric acids as other acids aren't suitable because they set up alternative redox reactions and hence make the titration reading inaccurate
What acid should you use for manganate titrations and why?
It doesn't disrupt the reaction mixture, using up the reactants and it leads to a much quicker determination of concentration
What advantage does using a spectrometer have to follow the reaction rate of the reaction between MnO4- and C2O42-?
Reduces it to only Cr3+
What affect does Fe2+ have on Cr2O72-?
Changing a ligand or oxidation state
What alters the energy split between the d orbitals?
The order of the reaction with respect to the reactant
What are 'm' and 'n' in the rate equation?
Hydration of ethene or fermentation of glucose
What are 2 ways of producing ethanol?
[M(H2O)6]2+
What are 2+ ions general formula
Fe (green) and Cu (blue)
What are 2+ ions?
During thermal cracking, during the reaction of halogens and methane, by homolytic fission
What are 3 examples of situations where a free radical can be formed?
[M(H2O)6]3+
What are 3+ ions general formula
Al (colourless) and Fe (violet)
What are 3+ ions?
Amphotheric
What are Al and Cl hydroxides classed as?
Molecules where the highest priority groups are on opposite sides
What are E isomers?
Molecules where the highest priority groups are on the same side
What are Z isomers?
Propane- 1, 2, 3-triol (glycerol) ester + fatty acids (long carboxylic acid chains)
What are animal, vegetable oils and fats composed of?
Phenols
What are aromatic alcohols known as?
Ligands that can form two co-ordinate bonds per ligand due to two atoms having lone pairs
What are bidentate ligands?
compounds with a C=O bond
What are carbonyls
- principle energy levels, 1,2,3,4 - 1 is closest to the nucleus
What are electrons arranged on?
sub energy levels called s,p,d,f
What are energy levels split into?
Free radicals
What are formed by homolytic fission?
Solids whereas the reactants are gaseous or in solution The reaction occurs at the surface of the catalyst
What are heterogenous catalysts usually?
Carbons with 0, 1, 2 or 3 other carbons attached
What are methyl, primary, secondary and tertiary carbocations?
The monomers which make up DNA made up of a phosphate group, a sugar and a base
What are nucleotides?
Clothing
What are polyamides and polyesters used for?
Easily to aldehydes, and then carboxylic acids
What are primary alcohols oxidised to?
Ions
What are produced by heterolytic fission?
Easily to ketones
What are secondary alcohols oxidised to?
Toxic gases released which need to neutralised via scrubbers
What are some of the disadvantages of burning plastic?
1) Requires a lot of land 2) As waste decomposes it releases methane (greenhouse gas) 3) As waste decomposes it releases toxins
What are some of the disadvantages of landfill (burying plastics)?
1) Lot of manpower/money invested in sorting plastics 2) Often can't remake the plastic we started with 3) Technically different to recycle plastics
What are some of the disadvantages of recycling plastic?
1) Inert (unreactive) 2) Non-toxic 3) Volatile (easy to remove)
What are some properties of tetramethylsilane (TMS) which make it suitable as a standard substance?
Molecules with the same molecular AND structural formula but a different 3D arrangement of their atoms in space
What are stereoisomers?
Molecules with the same molecular formula, but with different a structural formula
What are structural isomers?
Not oxidised under normal conditions, only break down under very vigorous oxidation
What are tertiary alcohols oxidised to?
1) 13C NMR - Gives info about how the carbon atoms in a molecule are arranged 2) 1H (or proton) NMR - how H atoms in molecule are arranged
What are the 2 types of NMR and what info do they provide?
Reduce Reuse Recycle
What are the 3 R's ?
Initiation, propagation, termination
What are the 3 steps of the chlorination of methane?
1. Reduce use of polymers in packaging 2. Reduce use of carrier bags 3. Dedicated polymer recycling 4. Use biodegradable polymers 5. Businesses MUST recycle polymers
What are the 5 strategies to reduce and manage polymer waste?
1. Prevent waste 2. Recycle and reuse 3. Safely dispose non-recyclable waste
What are the EU's policies on handling waste materials?
the bonds in CO2, methane and water vapour in the atmosphere do that cause global warming
What are the absorption of the bonds the same as?
No corrosive HCl fumes formed Cheaper
What are the advantages of anhydrides over acyl chlorides?
Saves money on transport as waste incinerated locally Prevents eyesores of landfills Heat of combustion used to power electricity generator
What are the advantages of incineration?
It can be added to rivers to remove poisonous heavy metal ions as the EDTA complexes are not toxic, it is is many shampoos to remove calcium ions present in hard water so helping lathering
What are the applications of EDTA complexes due to its stability?
Room temperature
What are the conditions in the electrophilic addition of bromine to an alkene?
Room temperature
What are the conditions in the electrophilic addition of hydrogen bromide to an alkene?
0 degrees
What are the conditions in the electrophilic addition of sulfuric acid to an alkene?
UV Light or possibly heat
What are the conditions needed for the chlorination of methane?
Reflux at 180°C
What are the conditions of the dehydration of an alcohol?
Reflux in alcoholic solution
What are the conditions of the nucleophilic elimination of an OH ion with a haloalkane?
Reflux in an aqueous, alcoholic solution
What are the conditions of the nucleophilic substitution of a cyanide into a haloalkane?
Reflux in an aqueous solution
What are the conditions of the nucleophilic substitution of a hydroxide into a haloalkane?
Reflux in aqueous, alcoholic solution under pressure
What are the conditions of the nucleophilic substitution of an ammonia into a haloalkane?
Hydrogen Cyanide, Potassium Cyanide Catalyst (Don't even think about doing it in the lab)
What are the conditions required for a Carbonyl to undergo Nucleophilic Addition with a cyanide ion?
Release toxic/greenhouse gases Gases can cause acid rain Still produces waste needs to be sent to landfill More expensive
What are the disadvantages of incineration?
Wastes and polluted land Polymers take hundreds of years to decompose Leach compounds into soil Eyesore Release methane (greenhouse gas)
What are the disadvantages of landfill?
4O and 2N
What are the donor sites on EDTA4-?
H₂O₂ + 2I⁻ + 2H⁺ → 2H₂O + I₂ 2S₂O₃²⁻ + I₂ → 2I⁻ + S₄O₆²⁻
What are the equations in the iodine clock reaction?
Weak van der Waals' forces
What are the forces between polymer molecules?
Complex formation Formation of coloured ions Variable oxidation state Catalytic activity
What are the four characteristics of transition metals
1. Reactants form bonds with atoms at active sites on the surface of the catalyst (adsorbed onto the surface) 2. As a result bonds in the reactants are weakened and break 3. New bonds form between the reactants held close together on catalyst surface 4. This is turn weakens bonds between product and catalyst and product leaves (desorbs)
What are the four steps in heterongeneous catalysis?
A carboxylic acid group and a primary amine
What are the functional groups on amino acids?
Permanent dipole-dipole attractions due to polar C=O bonds
What are the intermolecular forces between polyester chains?
Ni and Pt as they have about the right strength of adsorption
What are the most useful catalysts and why?
Polyester 2 x HCl
What are the products of the condensation reaction between a diacyl chloride and diol?
Concentrated phosphoric acid catalyst, 300°C, 60 atm
What are the reaction conditions of the hydration of ethene to make ethanol?
Chlorine and methane
What are the reagents in the chlorination of methane?
Tetrahedral
What are the shapes of Cu and Co chloride complexes?
Sample vaporised and passed through oven as a gas. Each component takes a different amount of time from being injected into the column to being recorded at the other end - retention time.
What are the steps of gas chromatography?
- orbitals which hold up to 2 electrons of opposite spin
What are the sub energy levels split into?
Hydrogen bonding between C=O and N-H Ionic attractions between positive and negative groups Sulfur-sulfur bonds between two cysteine molecules (a disulfide bridge)
What are the three types of bonding in amino acids and where does it occur?
1. Cl radical + O3 ----> ClO radical + O2 2. ClO radical + O3 ----> 2O2 + Cl radical
What are the two reactions in the Cl radical-catalysed conversion of O3 into O2?
Hydrogen bonding between bases
What are the two strands of DNA held together by?
Nylon - strong and resistant to abrasion so used to make clothing, carpet, rope and, parachutes Kevlar - Light and strong so bulletproof vests, tyres and boat construction
What are the uses of the above 2 materials?
Glycerol - Soluble in water so used in cosmetics and glues Soap - cleaning agents as it allows grease/oil and water to mix. Hydrophillic end + hydrocarbon hydrophobic end
What are the uses of the products of the hydrolysis of fats/oils?
Relatively weak intermolecular forces caused by temporary dipole dipole interaction
What are van der Waals forces?
Ions that have both a permanent positive and permanent negative charge but the compound is neutral overall
What are zwitterions?
Conc of the reactant doesn't change significantly Temperature remains constant When the end point is reached the reaction has not gone too far
What assumptions do we make when we use clock reactions?
A quantitative redox titration
What can Fe2+ and Cr2O72- in acid solution be used as?
Fe2+ and Cr2O72-
What can be used as a quantitative redox titration?
Further substitution, creating secondary or tertiary amines or a quaternary ammonium salt
What can happen if nucleophilic substitution of ammonia occurs without excess ammonia?
the molecular formula of a compound from the accurate mass of the molecular ion
What can high res mass spec be used to determine?
acids and alkalis
What can hydrolyse polyesters and polyamides?
provide information about types of bonds present in a molecule
What can infrared spectroscopy do?
m/z ratio and abundance
What can mass spec measure for each isotope?
1. The bonds within the reactant molecule becoming weaker 2. The molecules being held in a more reactive configuration 3. Higher concentration of reactants at the solid surface so leading to a higher collision frequency
What can reactants absorbing on the surface of the cataylst result in? (3 things)
chain, position and functional group isomerism
What can structural isomerism arise from?
See the bottom of the miniscus in the burette
What can the purple colour of the manganate make it hard to do?
3d and 4s electrons of atoms on the metal surface
What can transition metals use to form weak bonds to the reactants?
The balanced chemical equation
What can you not tell what the rate equation will be based solely on what?
Ligands
What causes the 5 d orbitals to split into two energy levels?
The Liebig condenser must be placed directly above the pear-shaped flask instead of to the side, so that any distilled aldehyde returns to the flask for further oxidation
What change in apparatus must be made to produce carboxylic acids instead of aldehydes?
All colourless
What colour are Ag+ complexes?
Orange to green
What colour change do primary or secondary alcohols cause in potassium dichromate?
None
What colour change do tertiary alcohols cause in potassium dichromate?
Permanent pink/purple colour Colourless -> Pink
What colour change will you expect at the end of the titration if the manganate is in the burette?
Change in gas volume Change in pH Colour change Change in mass
What could you measure when doing an experiment?
M(OH)3 ppt and CO2 gas is evolved
What do 3+ ions with carbonate form?
Bronsted-lowry bases, accepting a proton
What do NH3 and OH- ions act as?
They make this state unstable and easier to oxidise
What do ammonia ligands do to the Co(II)
To easily estimate the initial rate
What do clock reactions allow?
Oxidising agents e.g. MnO4-
What do compounds with high oxidation states tend to be? Give an example of one of these
Reducing agents e.g. V2+ and Fe2+
What do compounds with low oxidation states tend to be? Give an example
- the mathematical probabilities of finding an electron at any point within certain spatial distributions around the nucleus
What do orbitals represent?
formation of an ester linkage or an amide linkage
What do polyesters and polyamides involve?
An autocatalyst and therefore the reaction starts to speed up because they bring about the alternative reaction route with lower activation energy, the reaction eventually slows as the MnO4- concentration drops
What do the Mn2+ ions that are produced in the reaction between C2O42- act as?
Variable oxidation states
What do transition elements show?
Experimental data/conduct an experiment
What do you need to work out the rate equation?
[Al(OH)4]- (aq) colourless solution
What does Al become with OH-
Al forms white ppt of Al(OH)3 (H2O)3 + CO2
What does Al form in acidity reaction?
[Co(NH3)6]2+ Straw / yellow solution
What does Co become when H2O ligands are substituted for NH3 ligands? What colour is this?
[Cr(NH3)6]3+ Purple solution
What does Cr become when H2O ligands are substituted for NH3 ligands? What colour is this?
[Cu(NH3)4(H2O)2]2+ Deep blue solution
What does Cu become when H2O ligands are substituted for NH3 ligands? What colour
Fe(III) forms brown ppt of Fe(OH)3 (H2O)3 + CO2
What does Fe(III) form in acidity reaction?
H+ ions needed in mechanism
What does H2SO4 provide
nucleophilic CN- ions.
What does KCN/NaCN provide
Lewis base donating an electron pair
What does NH3 act as?
Chemical shift from the standard substance tetramethylsilane (TMS) - difference in frequency between resonating nucleus and that of TMS (measured in PPM)
What does NMR spectroscopy measure?
Nuclear Magnetic Resonance (NMR) Spectroscopy
What does NMR stand for?
[Fe(H2O)(OH)]2+ Goes from violet solution to brown solution
What does [Fe(H2O)6]3+ form on hydrolysis? What is the colour change?
Change in concentration of A will have no effect on the rate
What does a 0 order of reaction mean?
The rate is proportional to [A]
What does a 1 order of reaction mean?
The rate is proportional to [A]²
What does a 2 order reaction mean?
Oxidises it to Co(III)
What does air do to Co(II)
Change the frequency of light absorbed
What does altering the energy split between the d orbitals do?
it can act as both a base and an acid
What does amphoteric mean?
total number of particles present
What does area under curve represent?
Involved in the rate determining step
What does it mean if a reactant appears in the rate equation?
It is not involved in the rate determining step
What does it mean if a reactant does not appear in the rate equation?
The active site of the enzyme is so selective that enzymes only catalyses a reaction of one or the other of a pair of enantiomers
What does it mean if an enzyme is stereospecific?
Strength of the carbon-halogen bond
What does rate of reaction depend upon in nucleophilic substitution?
How the rate constant (k) varies with temperature and activation energy
What does the Arrhenius equation show?
A ligand substitution reaction
What does the addition of a high concentration of chloride ions (from conc HCl or saturated NaCl) to an aqueous ion lead to?
The effectiveness of the catalytic activity
What does the strength of adsorption help to determine?
Decreases time taken to reach equillibrium - has no effect on equillibrium composition
What effect does an acid have on the equillibrium reaction above?
The same effect as having insufficient sulphuric acid as it can not supply the large amount of hydrogen ions needed (8H+) The solution will not be acidic enough and MnO2 will be produced instead of Mn2+ The brown MnO2 will mask the colour change and lead to a greater (innacurate) volume of manganate being used in the titration
What effect will using a weak acid in a manganate titration have?
4s electrons
What electrons do transition metals lose to form ions first
Deprotonation reactions (similar to those of ammonia) forming hydroxide precipitates as it is a base
What else can ethane-1-2-amine carry out?
Ethane-1-2-diamine [Cu(H2O)6]2+ + 3NH2CH2CH2NH2 -> [Cu(NH2CH2CH2NH2)3]2+ +6H2O
What else is a common bidentate ligand? Draw an equation for this bidentate ligand substituting with water ligands in copper
The light that is not absorbed is transmitted to give the substance colour
What forms the substance colour?
Relative stability of +2 state increases with respect to +3 state
What happens across the period of transition metals?
Carboxylate ion salt formed + alcohol
What happens during the hydrolysis of esters through a base?
The hydrogen bonds holding the helix together can be permanently broken so wool loses its shape
What happens if you wash wool at high temperatures?
there are 2 different monomers that add together and a small molecule is usually given off as a side product
What happens in condensation polymerisation?
Visible light of increasing frequency is passed through a sample of a coloured complex ion
What happens in spectrometry?
Forms carboxylic acid + HCl (Steamy white fumes of HCl are given off)
What happens in the reaction between acyl chloride and cold water? State an observation
They decompose and a Cl radical is formed
What happens to CFCs under UV light?
The lone pair on the NH2 group accepts a proton to form a positive ion. The amino acid group has gained a hydrogen (protonated)
What happens to amino acids in strongly acidic conditions?
The OH group loses a proton to form the negative ion. The carboxylic acid group has lost a hydrogen ion (deprotonated)
What happens to amino acids in strongly alkaline conditions?
They partially dissociate into a caroboxylate ion and H+ ion
What happens to carboxylic acids in water?
One Cl ligand is substituted by a water molecule
What happens to cisplatin in the body?
A portion of visible light is absorbed
What happens to promote d electrons to higher enery levels?
Al hydroxide dissolves.
What happens when Al reacts with excess OH-
Their precipitates dissolve
What happens when Co, Cu and Cr undergo ligand substitution with NH3?
K increases
What happens when Ea decreases?
K decreases
What happens when Ea increases?
slowly to form the hydroxide but reacts more readily with steam to form the oxide
What happens when Magnesium reacts with cold water?
with a white flame to give a white solid smoke
What happens when Mg, Al, Si and P react with oxygen?
with a blue flame to form an acidic choking gas
What happens when S burns with oxygen?
K decreases
What happens when T decreases?
K increases
What happens when T increases?
Hydroxide dissolves, a colourless solution is formed
What happens when [Al(H2O)3(OH)3] (Al hydroxide) reacts with excess OH-?
Hydroxide dissolves, a green solution is formed
What happens when [Cr(H2O)3(OH)3] (Cr hydroxide) reacts with excess OH-?
the gradient of the curve is the ROR
What happens when a graph of concentration of reactant is plotted vs time
Green precipitate turn brown due to oxidation
What happens when an excess of OH- is added to Fe (II)
with a yellow flame to produce a white solid
What happens when sodium burns with oxygen?
it fizzes around on the surface
What happens when sodium reacts with cold water?
An amide linkage (-CONH-) is formed when water is released.
What happens when two amino acids join?
Secondary Amide + HCl formed (Steamy white fumes)
What happens when we react acyl chloride with a primary amine? State an observation
Amide + ammonium chloride produced (Steamy white fumes)
What happens when we react an acyl chloride with ammonia? State an observation
Ester + HCl formed (Steamy white fumes)
What happens when we react an acyl chloride with an alcohol? State an observation
results in MCO3 ppt being formed
What happens with 2+ ions with carbonate
- when forming ions they lose 4s before 3d - because they prefer a more stable full or half full d sub shell
What happens with chromium and copper?
goes to completion, and does not need a catalyst but does produce hazardous HCl fumes
What happens with more reactive acyl chloride?
cant hydrogen bond but have permanent dipole forces
What intermolecular forces are in carbonyls?
Al(H2O)3(OH)3 white ppt
What is Al hydroxide? What colour
Cr(H2O)3(OH)3 green ppt
What is Cr hydroxide? What colour
The highest priority groups are on the same side of the double bond
What is E-Z isomerism?
solution containing blue Cu2+ ions
What is Fehling's solution
(PD)^d x (PC)^c (PA)^a x (PB)^b
What is Kp for the reaction: aA + bB → cC + dD
The equilibrium constant for a reversible reaction where some or all the reactants and products are gases
What is Kp?
In electrophilic addition to alkenes, the major product is formed via the more stable carbocation
What is Markownikoff's Rule?
ethane-1,2-diol benzene-1,4-dicarboxylic acid
What is PET formed from?
Plastic bottles
What is PET used for?
PVC: Wellies, raincoats, uPVC: Drainpipes, window/door frames Electrical wire insulation
What is PVC used for?
Poly(chloroethene)
What is PVC?
The gas constant (8.31J K⁻¹ mol⁻¹)
What is R in the Arrhenius equation?
A proton acceptor
What is a base?
One that can be broken down in the environment by micro-organisms
What is a biodegradable polymer?
A renewable fuel made from plants
What is a biofuel?
A species which contains a positive charge on a carbon atom
What is a carbocation?
compounds with the same molecular formula but different structures of the carbon skeleton
What is a chain isomer?
A (z) isomer
What is a cis isomer?
A central metal ion surrounded by ligands
What is a complex?
A polymer formed when monomers join together and eliminate a small molecule such as water (or hydrogen chloride)
What is a condensation polymer?
Monomers join together and eliminate a small molecule such as water (or hydrogen chloride)
What is a condensation reaction ?
An atom or group with an unpaired electron, which is highly reactive as it wishes to pair up this electron
What is a free radical?
an atom or group of atoms which when present in different molecules causes them to have similar chemical properties
What is a functional group?
Too much land is being used to make biofuels rather than to grow food
What is a growing concern about biofuels?
A catalyst that is in a different phase from the reactants
What is a heterogenous catalyst?
A catalyst that is in the same phase as the reactant
What is a homogenous catalyst?
compound consisting of hydrogen and carbon only
What is a hydrocarbon?
An atom, ion or molecule which can donate an electron pair
What is a ligand?
molecule with one electron knocked off (both an ion and free radical)
What is a molecular ion?
An atom with a lone pair of electrons, which attack electron-deficient areas (those with a positive or slightly positive charge) on atoms
What is a nucleophile?
Diamine and dioic acid Diamine and diacyl chloride
What is a polyamide formed from? (2 possibilities)
A diol and dicarboxylic acid A diol and diacyl chloride
What is a polyester formed from ? (2 possibilities)
A long chain of repeating monomer units joined together
What is a polymer?
One which is attached to a carbon which is attached to 1 other carbon
What is a primary alcohol?
indication of an impurity
What is a rogue absorption?
One which is attached to a carbon which is attached to 2 other carbons
What is a secondary alcohol?
One which is attached to a carbon which is attached to 3 other carbons
What is a tertiary alcohol?
An (e) isomer
What is a trans isomer?
A ligand that can form one co-ordinate bond per ligand
What is a unidentate ligand?
the minimum energy which particles need to collide to start a reaction
What is activation energy?
A suitable ligand
What is added to pale colours to intensify the colour seen?
The reaction by which alkenes (or substituted alkenes) react with other alkene (or substituted alkene) molecules to form polymers
What is addition polymerisation?
A reaction in which two molecules join together to make one larger molecule
What is an addition reaction?
An unsaturated hydrocarbon
What is an alkene?
Pass vapour over a heated alumina (aluminium oxide) catalyst
What is an alternative method to reflux with strong acid to dehydrate an alcohol?
A positive ion or atom with areas of slightly positive charge, which attacks electron-rich areas such as C=C double bonds
What is an electrophile?
A substance which can accept a pair of electrons (electron pair acceptor)
What is an electrophile?
One in which a small molecule leaves the parent molecule
What is an elimination reaction?
A protein based catalyst found in living things
What is an enzyme?
The iodine clock reaction
What is an example of a clock reaction?
- atoms of the same element with the same number of protons but different numbers of neutrons
What is an isotope
A compound containing only carbon and hydrogen atoms and containing at least one carbon carbon double bond
What is an unsaturated hydrocarbon?
Where one of the products of the reaction can catalyse the reaction
What is autocatalysis?
fingerprint region
What is below 1500cm-1
A cancer drug
What is cisplatin?
When the shared pair of electrons in the covalent bond come from only one of the bonding atoms
What is co-ordinate bonding?
Purification of organic product
What is column chromatography mainly used for?
Involves two different monomer types, each with at least 2 functional groups. Each functional group reacts with a group on another monomer to form a link, creating polymer chains
What is condensation polymerisation?
Ligand exchange occurs without a change of co-ordination number
What is different about ligand substitution with Co and Cr vs. Cu
A biofuel or as a solvent
What is ethanol used as?
Cr2O72- (orange) -> Cr3+ (green) -> Cr2+ (blue) Reduced by Zn in HCl
What is formed by reduction of Cr2O72-? What is it reduced by? Give colour changes
Cr3+ and then Cr2+ due to reduction of Crr2O72- by zinc
What is formed when Zinc in Hcl is added to Cr2O72-?
to form hydroxides which are alkaline
What is formed when metal ionic oxides react with water?
Separating a mixture of volatile liquids
What is gas chromatography?
An iron(II) complex with a Multidentate ligand
What is haem?
Covalent bond breaks and both electrons move to one atom. Two oppositely charged ions are formed
What is heterolytic fission?
Where one ion gets both electrons from the covalent bond
What is heterolytic fission?
When catalysts and reactants are in the same phase, the reaction proceeds through an intermediate species
What is homogenous catalysis?
A reaction where each atom gets one electron from the covalent bond
What is homolytic fission?
Breaking up polymer into smaller unitz (monomers) via the addition of water - reversal of a condensation reaction
What is hydrolysis?
Continuous monitring
What is it called when you record at regular intervals the amount of product or reactant?
Distill off the aldehyde before it is further oxidised to a carboxylic acid
What is it essential to do when making aldehydes from alcohols?
The rate constant which links the concentration of reactants to the rate of a reaction
What is k and what does it do?
The proportion of a gas mixture that is made up of a particular gas
What is mole fraction?
heat under reflux
What is needed for oxidation of aldehydes
The intermediate will often have a different oxidation state to the original transition metal, at the end of the reaction the original oxidation state will reoccur
What is often a feature of an intermediate species in homogenous catalysis?
A support medium e.g. Rh on a ceramic support in catalytic converters
What is often used to maximise the surface area of a solid catalyst and minimise the cost?
Drawing a concentration-time graph, but sometime additional data may need to be collected to work out the concentration
What is one way to find the rate of reaction for an experiment?
Primary, secondary or tertiary alcohols
What is oxidation of alcohols used to differentiate between?
The pressure an individual gas exerts in a mixture of gases
What is partial pressure?
Emp - most probable energy
What is peak of curve?
Dilute sulfuric acid
What is potassium dichromate usually oxidised with?
It is bonded to four different groups so is chiral. Almost all naturally occurring amino acids exist as the - enantiomer
What is special about the carbon in the centre of an amino acid?
k=Ae^(-Ea/RT)
What is the Arrhenius equation?
ln(k) against 1/T
What is the Arrhenius plot?
~105° because the oxygen has two lone pairs which makes the functional group a V-shaped molecule
What is the C-O-H angle in an alcohol and why?
Incineration with energy recovery Incineration Landfill
What is the EU ranking of waste disposal methods?
Acidified Potassium Dichromate (K2Cr2O7)
What is the Oxidising Agent for Alcohols?
NaBrH4 OR LiAlH4
What is the Reducing agent for Carboxylics and Carbonyls?
Add a carbonate - CO2 formed and effervesence OR Universal indicator - red colour
What is the Test for a Carboxylic Acid?
Negative result with an oxidizing agent like Fehlings
What is the Test for a Ketone?
The place where the reactants adsorb on the surface of the catalyst
What is the active site?
most cost effective method of waste disposal
What is the advantage of landfill?
The concentration of the complex ion
What is the amount of light absorbed by the coloured complex ion proportional to?
A) Mobile phase - where molecules can move (always liquid/gas) B) Stationary phase - where the molecules can't move (solid, or liquid on a solid support)
What is the basic set-up common across all types of chromatography?
-COOH
What is the carboxylic functional group?
Coordination number of 6 = octahedral shape Bond angle around Cr 90 degrees
What is the co-ordination number of a molecule with ethane -1-2-diamine ligands? What are the bond angels around the central metal ion?
The number of co-ordinate bonds formed to a central metal ion
What is the co-ordination number?
Blue
What is the colour of Cr2+
Orange
What is the colour of Cr2O72-?
Green
What is the colour of Cr3+
Purple
What is the colour of MnO4-
Ethanol, along with a small amount of poisonous methanol and a purple dye
What is the composition of methylated spirits?
Yeast, 35°C, aqueous, anaerobic conditions
What is the conditions of the fermentation of glucose?
Saturated - contains no double bonds
What is the difference between a saturated and unsaturated fatty acid?
Primary has 1 carbon chain coming off, secondary 2, tertiary 3
What is the difference between primary, secondary and tertiary amines?
A plasticiser molecule has been added to PVC to make it more flexible for its use in clothing
What is the difference between uPVC and PVC?
deltaE = hv v = frequency of light absorbed (s-1) h = Planck's consant 6.63x10-34 J s deltaE = energy difference between the split orbitals j
What is the equation that links the colour and frequency of the light absorbed with the energy difference between the split d orbitals?
will compare the IR spectra against a database of known pure compounds to identify the compound
What is the fingerprint region?
- enthalpy change when one of gaseous atoms forms one mole of gaseous ions with a single positive charge: H(g) -> H+ (g) + e-
What is the first ionisation energy?
(H3N)2Pt(Cl)2
What is the formula fro cisplatin?
[Cu(NH3)4(H2O)2]2+ deep blue solution
What is the formula of the Cu after substitution and what colour is it?
-COCl, CnH2n-1OCl
What is the functional group + general formula of acyl chlorides?
CnH2n
What is the general formula for an alkene?
RCOOR'
What is the general formula for esters?
CnH2n+1OH
What is the general formula of an alcohol with no carbon rings?
H2NCHRCOOH
What is the general formula of an amino acid?
rate at the start of the reaction where it is fastest
What is the initial rate?
A line indicating the relative heights of the steps of this trace and gives the relative number of each type of hydrogen
What is the integration trace?
the lewis base because it is donating a pair of electrons in the dative covalent bond and the metal ion is the Lewis acid
What is the ligand in the formation of complex ions?
Mobile phase A liquid solvent such as ethanol Stationary phase - thin layer of silica/alumina fixed to a glass or metal plate
What is the mobile and stationary phase of TLC
number of moles of gas = mole fraction x total number of moles in mix
What is the mole fraction formula?
Acid anhydrides produce the same carboxylic acid that made the anhydride, where acyl chloride produce HCl.
What is the only difference between reactions of acyl chlorides and acid anhydrides of the above?
m+n
What is the overall order of reaction?
2O3 ----> 3O2
What is the overall reaction for the conversion of ozone into oxygen?
partial pressure = mole fraction x total pressure
What is the partial pressure formula?
The sequence of amino acids held together by covalent bonding
What is the primary structure of a protein?
alkylhydrogensulfate
What is the product of the addition of H2SO4 to an alkene called?
Alkene
What is the product of the dehydration of an alcohol?
An alkene
What is the product of the nucleophilic elimination of an OH ion with a haloalkane?
A nitrile
What is the product of the nucleophilic substitution of a cyanide into a haloalkane?
An alcohol
What is the product of the nucleophilic substitution of a hydroxide into a haloalkane?
A primary amine
What is the product of the nucleophilic substitution of an ammonia into a haloalkane?
An alcohol
What is the product when water is electrophilically added to an alkene?
Used as an indicator that changes to blue-black in the presence of iodine
What is the purpose of starch in the iodine clock reaction?
Rate = k [A]^m[B]^n
What is the rate equation for the experiment A + B → C + D?
the change in concentration of a substance per unit time - mol dm-3s-1
What is the rate of reaction?
Nucleophilic Addition
What is the reaction mechanism associated most associated with Carbonyls?
The change in amount of reactant or product per unit time
What is the reaction rate?
Bromine (either as a neat liquid or dissolved into tetrachloromethane)
What is the reagant in the electrophilic addition of bromine to an alkene?
Hydrogen bromide
What is the reagant in the electrophilic addition of hydrogen bromide to an alkene?
Concentrated (85%) Sulfuric acid
What is the reagant in the electrophilic addition of sulfuric acid to an alkene?
Alcoholic sodium/potassium hydroxide
What is the reagant in the nucleophilic elimination of an OH ion with a haloalkane?
Concentrated sulfuric/phosphoric acid
What is the reagent in the dehydration of an alcohol?
Water with strong acid (sulfuric or phosphoric acid)
What is the reagent in the electrophilic addition of water to an alkene?
Aqueous, alcoholic potassium/sodium cyanide
What is the reagent of the nucleophilic substitution of a cyanide into a haloalkane?
Sodium or Potassium Hydroxide aqueous solution
What is the reagent of the nucleophilic substitution of a hydroxide into a haloalkane?
Aqueous, alcoholic ammonia (in excess)
What is the reagent of the nucleophilic substitution of an ammonia into a haloalkane?
- enthalpy change when one mole of gaseous ions with a single positive charge forms one mole of gaseous ions with a double positive charge: H+(g) -> H2+ (g) +e-
What is the second ionisation energy?
A protein forms an alpha helix of a beta pleated sheet. They are both held by hydrogen bonds
What is the secondary structure of a protein?
tetrahedral and the bond angle is 109.5
What is the shape and bond angle around the carbon atom in saturated hydrocarbons?
C=O group
What is the specific functional group determining a Carbonyl?
The alpha helix or beta pleated sheet is folded into a 3D shape held together by hydrogen bonds, ionic attractions and disulfide bridges (as well as van der waals)
What is the tertiary structure of a protein?
When a reaction has a series of steps, the step with the slowest rate is called the rate determining step
What is the the rate determining step?
All the partial pressures added together
What is the total pressure of a gas mixture?
ionic metal oxides show basic behaviour and non metal covalent oxides show acidic behaviour
What is the trend in terms of acid/basic behaviour?
Acidified potassium (VI) dichromate
What is the usual reagent in the oxidation of alcohols?
[Co(NH3)6]3+ when standing in air Yellow solution
What is this Co NH3 complex oxidised to and when? What colour?
Carbohydrates such as sugar cane, sugar beet, rice and maize
What is used as a source of glucose in fermentation?
Adsorption of visible light
What is used in spectrometry to determine the concentration of coloured ions?
Electrophile has been added across the double bond
What key phrase is used to describe how the C=C bond is broken by electrophiles?
The substitution of unidentate ligands with a bidentate or a multidentate ligand As there is a positive entropy change in these reactions are more molecules of products than reactants
What leads to a more stable complex? Why?
Catalytic action
What may adsorption of reactants at active sites lead to
Square planar Cisplatin
What other shape complexes can be formed? Give an example of a complex like this
+1
What oxidation state do all silver complexes have?
Poly(ethene)
What polymer would the monomer ethene form?
1:1
What ratio does EDTA4- form with metal (II) ions?
Cl2 ----> 2Cl free radicals
What reaction occurs during the initiation step of the chlorination of methane?
a ligand substitution occurs with Cu and its precipitate dissolves (incomplete)
What reaction occurs with Cu and excess NH3
Tetrahedral
What shape complexes do transition metal ions form with larger ligands?
Octahedral complexes
What shape complexes do transition metals typically form with small ligands?
Octaherdral and 90 degree bond angles [Cu(H2O)6]2+ + 3C2O42- -> [Cu(C2O4)3]4- + 6H2O [Cr(H2O)6]3+ + 3C2O42- -> [CrC2O4)3]3- + 6H2O
What shape is an ethandioate complex and what are the bond angles? Equation for substitution of ethandioate ligands with aqueous copper and aqueous solution
Linear complexes
What shaped complexes does Ag+ form?
The oxidation number of the vanadium changes but then changes back it is still classed as a catalyst as it returns to it's original form
What should you note about the catalyst in the contact process?
A pleasant one
What smell do most aldehydes and ketones have?
Free radical substitution
What sort of reaction is the chlorination of methane?
To accept a proton (act as a base)
What tendency does the amine group have on an amino acid?
To lose a proton (act as an acid)
What tendency does the carboxylic acid group have on an amino acid?
Polyester Contains many COO (ester) groups
What time of condensation polymer is PET and why?
The Pt(II) complex cisplatin
What transition metal complex is used as an anti cancer drug?
H and OH
What two species are added to the carbons either side of the double bond when water is electrophilically added to an alkene?
Co-ordinate bonding
What type of bonding is involved in complex formation?
Linear complexes
What type of complexes does Ag+ form?
Polyamide
What type of condensation polymer is nylon-6,6 ?
Metal aqua ions
What type of ions are formed in aqueous solution?
E-Z stereoisomerism
What type of isomerism can alkenes exhibit
Cr3+
What will Fe2+ reduced dichromate ions to?
then a M+2 and a M+4 peak will occur
What will happen if a compound contains two chlorine or bromine atoms
they will be reduced to alcohols
What will happen in reduction of carbonyls?
The solution will not be acidic enough and MnO2 will be produced instead of Mn2+ The brown MnO2 will mask the colour change and lead to a greater (innacurate) volume of manganate being used in the titration
What will happen in the redox titration using manganate if insufficient sulphuric acid is added? What problem will this cause?Write equation
original monomers forming - although carboxylic acid or amine group will be in salt form depending on whether the conditions are alkaline or acidic
What will hydrolysis result in?
Increasing the surface area
What will improve the effectiveness of a solid catalyst?
The first permanent pink colour Colourless -> Pink
What will the end point of the titration be if your using manganate in the burette?
Their partial pressures will be the same
What will the partial pressure be if the gases are present in equal quantities?
Brady's reagent (2,4 DNPH) Orange to yellow precipitate
What's the Test for a Carbonyl group?
Oil is a liquid at room temperature whereas fats are solid
What's the difference between a fat and an oil?
Tollens reagent - Silver mirror test OR Fehling's/Benedict's reagent blue to brick red
What's the test for an Aldehyde?
- a molecule with two atoms e.g. Cl2
Whats a diatomic molecule and example?
Just the atoms and bonds (single covalent) There should be no brackets or n
When asked to draw the repeating unit what should you draw?
When there is restricted rotation around the C=C double bond. THere are two different groups/atoms attachd both ends of the double bond
When do stereoisomers arise?
when unsaturated monomers react to form a polymer
When does an addition polymer form?
When there is a change in temperature
When does k change?
When the reaction is the same and the temperature is not increased
When does k not change?
the same hydroxide precipitates in deprotonation acid base reactions
When in limited amounts, OH- and NH3 form?
- for elements and substance with low formula mass - can cause larger organic molecules to fragment
When is electron impact used?
- preferably larger organic molecules - softer conditions mean fragmentation doesn't occur
When is electrospray used?
if the C=O is in the middle of the chain
When is it a ketone?
when C=O is on the end of the chain with an H attached
When is it an aldehyde?
in solid hydrated salts that contain these complexes
When is the violet colour seen?
When a dilute solution containing ethanedioate ions is added to a solution containing aqueous copper ions. In this reaction four water molecules are replaced and a new complex is formed [Cu(H2O)6]2+ + 2C2O42- -> [Cu(C2O4)2(H2O)2]2- + 4H2O
When may partial substitution of ethanedioate ions occurr? Write the equation for this reaction
Alkaline solutions
When transition metals are in low oxidation states are they more easily oxidised by alkaline solutions or acidic solutions?
When the (intermolecular) van der Waals forces are overcome
When will a polymer melt?
when there is an equal chance of either enantiomer forming and no optical activity is seen
When will a racemate form?
Directly to the ring
Where is the OH attached in aromatic alcohols?
always on carbon 1
Where is the functional group on aldehydes, carboxylic acids and nitrils
3+ due to the greater polarising power, electrons in metal-o bond get pulled towards the metal, this in turn weakens the o-h bond exposing the nuclei of hydrogen
Which is more acidic - the aqueous solutions of metal ions with 3+ or 2+
Metal oxides Na2O, MgO, Al2O3
Which oxides are ionic?
Sodium/potassium hydroxide and water
Which two reagants can turn a haloalkane into an alcohol?
Tertiary is the most stable, methyl is the least stable
Which type of carbocation is the most and which is the least stable?
Those with short hydrocarbon chains because this allows the hydrogen bonding from the alcohol group to water molecules to dominate
Which types of alcohols are soluble in water and why?
Each repeating unit has 2 ester/amide groups
Why are 2 molecules of water eliminated for the formation of one repeating unit ?
They lack the reactive carbon-carbon double bond Which is an area of high electron density And so vulnerable to electrophilic attack
Why are addition polymers unreactive?
Contain C=C double bond Area of high electron density
Why are alkenes vulnerable to electrophilic attack?
The polymer chains cannot pack closely together van der Waals' between chains weaker
Why are branched polymers weaker and softer?
As the reaction has an increase in entropy because of the increase in moles from 4 to 7. Delta S is positive, delta H is close to zero as the number of dative covalent and type (N to metal coordinate bond) are the same so the energy required to break and make bonds will be the same. Therefore free energy delta G will be negative = complex is stable
Why are complexes formed with ethane-1-2-diamine stable?
Bonds between repeating units are polar and so are susceptible to attack by nucleophiles such as water
Why are condensation polymers biodegradable?
Can be hydrolysed by microorganisms as polar C=O group is vulnerable to nucelophilic attack
Why are condensation polymers biodegradable?
Condensation polymers made up of chains consisting of polar bonds so there are permanent dipole-dipole forces as well as induced ones and H bonds
Why are condensation polymers more reactive than addition polymers?
oxide ions accept protons to become hydroxide ions in this reaction
Why are ionic oxides basic?
Chemically inert because they are saturated No bond polarity
Why are polyalkenes non-biodegradable ?
Very compact Chains can pack together van der Waals' strong
Why are polymers with very few branches strong and hard?
because of the small electronegativity difference between non metal and O atoms
Why are simple molecular structures covalent?
because they can form hydrogen bonds with water
Why are smaller carbonyls soluble in water?
- when 1st electron is removed a positive ion is forms, the ion increases the attraction on the remaining electrons and so the energy required to remove the next electron is larger
Why are successive ionisation energies always larger?
Hydrogen bonds between the O of C=O and the H of N-H in polyamide chains Stronger than the weak van der Waals' between polyalkene chains
Why are the intermolecular forces between polyamides greater than those between polyalkenes?
Chains are often long Many electrons Many van der Waals'
Why are the intermolecular forces between polymers often strong?
large electronegativity difference between the metal and the O
Why are they ionic?
Because unlike in short chain hydrocarbons the long, non-polar hydrocarbon chain dominates over the hydrogen bonding
Why aren't alcohols with long hydrocarbon chains soluble in water?
Due to the colour changes
Why can Fe2+ and Cr2O72- be used as a quantitative redox titration?
There are stronger intermolecular forces between polymer chains Hydrogen bonding in polyamides Permanent dipole-dipole attractions in polyesters Fibres can be woven/knit together
Why can polyamides and polyesters be used for clothing?
Lack of an adjacent hydrocarbon
Why can some alcohols not be dehydrated?
There are only weak van der Waals' forces between polymer chains
Why can't addition polymers be used to make clothing?
As it is an oxidising agent, it would oxidise Fe2+ to Fe3+ as the E standard value for NO3-/HNO2 is greater than the E standard value for Fe3+/Fe2+ This would lead to a smaller volume of manganate being used
Why can't concentrated HNO2 be used in a manganate titration?
As the Cl- ions would be oxidised by MnO4- as the Estandard value of MnO4-/Mn2+ is greater than the Estandard value for Cl2/Cl- This would lead to a greater volume of manganate being used and poisonous Cl2 being produced
Why can't concentrated Hcl be used in a manganate titration?
As lead strongly adsorbs onto the surface of the catalyst aka poisons it
Why can't leaded petrol be used in cars with catalytic converters?
As it doesn't have a partially filled d subshell therefore it is not able to do electron transitions between d orbitals
Why can't silver form colour compounds?
- outer electrons found in shells further from nucleus, more shielding so attraction is weaker
Why do 1st IE decrease down a group
- electrons being added to same shell, same distance from nucleus and shielding, but more protons - stronger attraction
Why do 1st IE increase across a period
because of the high strength of the Al2O3 ionic lattice and the SiO2 macromolecular structure so they give a neutral pH of 7
Why do Al2O3 and SiO2 not dissolve in water?
Because of their low bond enthalpy
Why do Cl2 molecules produce chlorine free radicals when exposed to UV light?
- they have the same electronic structure
Why do Isotopes have similar chemical properties?
d shell is full 3d10 No space for electron transfer No energy transfer equal to that of visible light
Why do Zn2+ and Cu+ form compounds without colour?
Because they can form hydrogen bonds, which are not present in alkanes
Why do alcohols have a much higher boiling point than alkanes with a similar molecular mass?
Less surface area Fewer/weaker van der Waals'
Why do branched polymers have a lower boiling point that straight chain polymers?
They have varying levels of shielding
Why do carbon atoms in different environments feel the magnetic field differently?
More water available in compost to hydrolyse polymer More oxygen available Warmer More UV light More bacteria
Why do condensation polymers break down more quickly in compost than landfill?
- different masses
Why do isotopes have varying physical properties
Consist of chains of different lengths varying strength of van der Waals'
Why do some polymers melt over a range of temperatures?
Because this weakens their van der waals' forces
Why do the boiling points of alcohols decrease as branching increases?
Increased chain length leads to an increase in van der waals' forces
Why do the boiling points of alcohols increase as chain length increases?
Because the conc. of the reactants has not changed and neither has the orders of reaction so it must be an increased in k that has increased the rate of the reaction
Why do we know that temperature affects k?
- first electron in first shell closest to nucleus, no shielding, more than hydrogen as it has one more proton
Why does Helium have largest 1st IE?
- Na has its outer electron in 3s, further from nucleus and more shielding so easier to remove
Why does Na have lower than Ne
because its a bigger molecule and has more electrons so will have larger VDW forces and a higher mp
Why does P4O10 have a higher mp?
It has no d electrons left to move So there is no energy transfer equal to that of visible light
Why does Scandium have no colour?
One bonded to oxygen has less shielding as Oxygen is more electronegative. It is deshielded so feels a greater magnetic field and hence resonates at a higher frequency
Why does a carbon bonded to oxygen have a greater chemical shift than one bonded to another carbon?
Hair cells replicate quickly
Why does cisplatin make people's hair fall out?
because there are no molecules with no energy
Why does it go through the middle?
no maximum energy for molecules
Why does it never meet x axis?
- otherwise air particles would ionise and register on the detector
Why does mass spectrometer need to be under a vacuum?
because theres increased charge on the cation making the ionic forces stronger - bigger lattice enthalpies of dissociation
Why does melting point increase from Na - Al
As the two chloride ions are displaced and the molecule joins on to the DNA - in doing this it stops the replication of cancerous cells
Why does only the cisplatin version work?
Because at this concentration the enzymes in the yeast are denatured
Why does the fermentation of glucose stop after the solution reaches around 15% ethanol concentration?
Because the atomic radius of the halogen increases as you go down the group, so the area of the covalent bond also increases, making it easier for electrons to be removed
Why does the strength of the carbon-halogen bond decrease as you go down the group?
ionic but shows covalent character
Why is Al2O3 different?
As it can form a strong co-ordinate bond with haemoglobin This is a stronger bond than that made with oxygen and so it prevents the oxygen attaching to the haemoglobin
Why is CO toxic to humans?
This is due to the greater polarising power of the 3+ ion due to it's higher charge density
Why is MCO3 formed by 2+ ions but M2CO3 is not formed by 3+ ions?
as its lattice is stronger so fewer free OH- ions are produced and so lower pH
Why is Mg(OH)2 only slightly soluble in water?
it is only sparingly soluble and weakly alkaline so using an excess would not make the water excessively alkaline
Why is MgO better than NaOh for treating acid in rivers and the stomach?
contains a source of nucleophilic hydride ions which are attracted to positive carbon in C=O bond
Why is NaBH4 used?
to stop these elements coming into contact and reacting with air
Why is Sodium stored under oil and phosphorus under water?
It can only form a 2+ ion - Zn2+ has a complete d-orbital
Why is Zn not a transition metal?
reacts and dissolves in both acids and bases
Why is [Al(OH)4]- classed as amphoteric
the slightly intermediate nature of the bonding
Why is aluminium amphoteric?
Contains many amide groups
Why is nylon-6,6 a polyamide?
Reduces waste Conserves resources
Why is recycling important?
Has 12 hydrogen atoms all in identical environments and 4 carbon atoms in identical environments meaning it produces a singular peak for both types of NMR
Why is tetramethylsilane (TMS) used as the standard substance?
because O is more leectronegative than carbon,
Why is the C=O bond polarised?
because of the greater polarising power of the 3+ metal ion. The greater the polarising power, the more strongly it attracts the water molecule. This weakens the O-H bond so it breaks more easily
Why is the acidity of 3+ more than that of 2+
Because during the propagation step, one radical is produced for each one used
Why is the chlorination of methane a chain reaction?
Because the reaction involves two negative ions which repel each other leading to a high activation energy
Why is the initial un catalysed reaction between C2O42- and MnO4- slow?
As the reaction is between two negative ions Heat the conical flask to 60 degrees to speed up the initial reaction
Why is the reaction between MnO4- and C2O42- slow to begin with? How would you do this reaction as a titration?
Because of the significant colour change from reactant to product
Why is the reaction between MnO4- and Fe2+ self indicating?
Because the reaction needs a collision between two negative ions. Repulsion between ions is going to hinder this - meaning a high activation energy
Why is the uncatalysed reaaction between I- and S2O82- very slow?
As Cl- is larger than the uncharged H2O and NH3 ligands
Why is there a change in co-ordination number when ligand substitution reactions with Cl- occurs?
Wool is a protein fibre with a helix that is held together by hydrogen bonds. When wool is stretched the hydrogen bonds stretch and the fibre extends.
Why is wool stretchy?
It binds to the DNA in all cells, not just cancer cells so can damage cells and make a person feel ill.
Why might cisplatin not be effective as a drug?
So that the ethanol produced is not then oxidised to ethanoic acid
Why must fermentation occur under anaerobic conditions?
Too big a drop will cause different spots to merge
Why must the drops of the sample be very small?
Lines won't dissolve in solvent
Why must we use a pencil to draw lines?
M and M2+ due to the two naturally occurring isotopes of Chlorine and Bromine
Why will 2 peaks occur when a compound contains Br or Cl
SiO2 has a giant covalent structure with very strong bonds
Why will SiO2 not react with water or weak alkali?
it is a toxic gas that is difficult to contain
Why would you not use HCN?
No
Will a Carboxylic Test positive as a Carbonyl?
No, catalysts only affect the time it takes for equilibrium to be reached
Will a catalyst affect Kc and Kp? Why?
No, as the position of the equilibrium shifts in such a way that the partial pressures at the new equilibrium keep Kp constant
Will pressure affect Kc and Kp? Why?
Yes, as the equilibrium of the system will shift
Will temperature affect Kc and Kp? Why?
Cu, Co and Cr
With excess NH3 ligand substitution occurs with which ions?
sum of all (isotopic mass x percentage)/ 100
Work out RAM with percentage abundance?
sum of all (isotopic mass x abundance)/ total relative abundance
Work out RAM with relative abundance?
Colourless solution to White ppt
Write the balanced equation for the reaction when carbonate is added to Al aqueous ions. State the colour change.
Red/violet solution to Green ppt
Write the balanced equation for the reaction when carbonate is added to Cr aqueous ions. State the colour change.
Brown solution to Brown ppt
Write the balanced equation for the reaction when carbonate is added to Fe (III) aqueous ions.
A precipitate
Write the formula for 2+ ions reacting with limited OH-/NH3. What is formed?
A precipitate
Write the formula for 3+ ions reacting with limited OH-/NH3. What is formed?
Blue solution
Write the formula for the Co Cl complex formed. What colour is this?
Yellow-green solution
Write the formula for the Cu Cl complex formed. What colour is this?
White ppt and fizzing
Write the formula for the products that are formed when carbonate is added to Al aqueous ions. Observations.
Green ppt and fizzing
Write the formula for the products that are formed when carbonate is added to Cr aqueous ions. Observations.
Brown ppt and fizzing
Write the formula for the products that are formed when carbonate is added to Fe (III) ions. Observations.
Any indication that a measuring system gives a false reading when the true value of a measured quantity is zero, eg the needle on an ammeter failing to return to zero when no current flows. A zero error may result in a systematic uncertainty.
Zero error.
complementary - means they match up so that whenever there is an A on one strand there will be a T on the other
bc A only pairs with G and C only pairs with T, what does this make the strands and what does it mean
1. draw a pencil line nr the bottom of a TLC plate and put a concetrated spot of the mixture of AAs on it 2. dip the bottom of the plate (not the spot) into the solvent 3. as the solvent spreads up the plate the diff AAs move w it but at diff rates so they separate out 4. when the solvents nearly reached the top take the plate out and mark the solvent front with pencil then leave the plate to dry 5. spray ninhydrin solution on the plate which turns the spots purple so you can see them 6. work out Rf values for each AA spot 7. use a table of know AA Rf values to identify the AAs
briefly describe how to carry out TLC
it binds to DNA causing kinks in the DNA helix which stop the proteins that replicate the DNA from copying it properly so stops tumour cells reproducing
briefly how does cisplatin work
Cu - blue ppt Fe (II) - green ppt
colour of 2+ ions
Cu- Blue/green Fe(II) green
colours of MCO3 ppts?
H bonds exist between polar groups like -OH and -NH2 and they stabilise the secondary and tertiary structure of the protein
describe H bonding in a protein
its 3D and part of the tertiary structure of the enzyme protein
describe the active site
bc the balance of the long term positive effects (curing cancer) outweigh the negative short-term effects
despite the side effects, why is cisplatin still used as an anti-cancer drug
- Al starting to fill 3p subshell, Mg has its outer electrons in 3s - electrons in 3p are easier to remove as they are higher in energy and shielded by 3s
drop from Mg - Al
- Sulphur has 4 electrons in £p and 4th is doubly filling first 3p orbital - when the second electron is added to a 3p orbital there is repulsion between the negatively charged electrons making second electron easier to remove - shielding stays the same
drop from P-S
Ch3CHO + 2Ag+ + H2O -> CH3COOH + 2Ag +2H+
equation for Aldehyes and Tollens reagent
H(n+1)+(g) -> Hn+(g) + e-
equation for any succesive ionisation energy?
[Al(H2O)6]3+(aq) + 3OH- (aq) -> Al(H2O)3(OH)3 (s) + 3H2O (l)
equation of Al3+ with OH
[Cu(H2O)6]2+(aq) + 2OH- (aq) -> Cu(H2O)4(OH)2(s) + 2H2O (l)
equation of Cu2+ with OH
[Fe(H2O)6]2+(aq) + 2NH3 (aq) -> Fe(H2O)4(OH)2(s) + 2NH4+ (l)
equation of Fe2+ with NH3
[Fe(H2O)6]3+ (aq) + 3NH3 (aq) -> Fe(H2O)3(OH)3 (s) + 3NH4+ (aq)
equation of Fe3+ with NH3
2CH3CO2H + Na2CO3 -> 2CH3CO2-Na+ + H2O + CO2
equation of testing for carboxylic acid
RCHO + [O] -> RCO2H
general equation for oxidation
e.g. antibiotics work by blocking the active site of an enzyme in bacteria that helps to make their cell walls so this causes their cell walls to weaken over time so the bacteria eventually burst
give an example of how a drug works as an inhibitor
chloro, bromo, iodo
halogenoalkane prefix?
by trial and error - scientists carry out experiments using lots of compounds to see if they work as inhibitors for a particular enzyme, they then adapt any that work to try and improve them which takes a long time
how are new drug molecules often found
by giving patients very low dosages OR to just target the tumour by using a method that delivers the drug only to the cancer cells so it doesnt get the chance to attack healthy cells
how can the side effects of cisplatin be lessened
thiol groups on diff cysteines can lose their H atoms and join together by forming a disulfide bond (-S-S)
how do disulfide bonds form
they block the active site of an enzyme and stop it from working
how do drugs as inhibitors work
by condensation polymerisation
how does DNA form
from the NH in the base that isnt next to a double bond and to the -OH on the sugar
how does the base bond to the pentose sugar
covalent bonds form between the phosphate group of one nucleotide and the sugar of another by condensation polymerisation
how is the sugar phosphate backbone formed and by what process
2
how many H bonds do A and T form
3
how many H bonds do G and C form
between a polar positive H atom (an H attached to anything highly electronegative like N) and a lone pair of electrons on a nearby O or N atom
in base pairing, where does a H bond form
1. a N atom on a guanine base in DNA forms a coordinate bond with cisplatin's platinum ion, replacing one of the chloride ion ligands (ligand substitution) 2. a second N atom from a nearby guanine (either on the same strand of DNA or the opp strand) can bond to the platinum and replace the second chloride ion ligand 3. the presence of the cisplatin complex bound to the DNA strands causes them to kink (this damage leads to the death of the cell) so the DNA strands cant unwind and be copied properly so the call cant replicate
in detail, describe how cisplatin works
compounds with the same molecular formula but different structures due to different positions of the same functional group on the same carbon skeleton
position isomers?
cysteine
what AA contains a thiol group
the 3D shape that is affected by the IM forces
what affects how a protein functions
how soluble it is in the solvent youve used
what affects how far and at what rate each AA moves up the TLC plate
depends on the relative concs of the inhibitor and substrate - if theres a lot more inhibitor then it'll take up most of the active sites and v little substrate will be able to get to the enzyme and also how strongly the inhibitor bonds to the active site
what affects how much inhibition happens
proteins that act as biological catalysts by speeding up chemical reactions and some also have non-protein components
what are enzymes
AAs
what are enzymes made up of
a phosphate group, a pentose sugar and a base
what are nucleotides made up of
condensation polymers of AAs
what are proteins
lots of AAs joined together by peptide links
what are proteins made up of
the molecules that enzymes act on to speed up reactions
what are substrates
adenine, cytosine, guanine and thymine
what are the 4 bases in DNA
hot aq 6M HCL and heat under reflux for 24hrs
what are the conditions needed for hydrolysis of a protein
peptide links
what are the links called in proteins
a dipeptide and a water molecule
what are the products when two AAs join together
primary, secondary and tertiary
what are the three levels of structure in a protein
H bonding and disulfide bonds
what are the two main types of IM forces in a protein
a dipeptide
what are two AAs joined together called
a covalent phosphodiester bond
what bond is formed when two nucleotides join together
zwitterions
what can amino acids exist as
the IM forces
what causes the AA chains to fold and twist in the secondary and tertiary structures
temp and pH
what conditions can affect H bonding and the formation of disulfide bonds and hence change the shape of proteins
link together diff part of the protein chain, and help to stabilise the tertiary structure
what do disulfide bonds do
catalyse every metabolic reaction in the bodies of living organisms
what do enzymes do
slow down the rate of reaction by competing with the substrate to bond to the active site but no reaction takes place, instead they just block the active sit so no substrate can fit in it
what do inhibitors do
a similar shape to the substrate
what do inhibitors have to have
c=c bonds
what do monomers contain?
the right distance apart
what do the two atoms have to be in order to bond in base pairing
all the genetic info of an organism
what does DNA contain
deoxyribonucleic acid
what does DNA stand for
replicate its DNA
what does a cell have to do in order to divide
its R group
what does an AAs isoelectric point depend on
an organic side-chain
what does an R stand for
it binds to DNA in cancer cells and so is used as an anti cancer drug
what does cisplatin do
an active site
what does every enzyme have
attracts nucelophiles
what does postiive carbon atom do?
the active site will only work with one of the enantiomers of a substrate, the other wont fit properly in the active site so the enzyme cant work on it
what does stereospecific mean
