Chem 325 Lab Final
In case of a chemical spill to your eyes, you should use the eye wash station continuously for
15 minutes
You notice that your TA is looking pale, and then you see him collapse on the floor. What should you do? Select all correct answers
Stay with your TA to monitor his status, and send someone to report the incident using the red emergency phone in the hallway. Safely stop all experimentation. Calmly wait for UD Public Safety to arrive and assist.
Thin Layer Chromatography (TLC)
A type of chromatography that uses silica gel or alumina on a card as the medium for the stationary phase. use pencil w light pressure
Silver Nitrate Test
Test that uses silver nitrate solution to identify halide ions in solution. a positive test is consistent with the presence of a secondary, tertiary, alkyl halide, but not primary
seperation of a mixture
start w 1:1:1 mixture of benzoic acid, ethyl 4-aminobenzoate, and biphenyl dissolve in diethyl ether and add 5% HCL, then add 5% NaOH dry w sodium sulfate filter pipette into vial and evaporate ether neurtralize both water layers to obtain respective compounds, filter through hirsh funnel to obtain crystals
Thin layer chro
stationary- silica gel mobile- eluent/solvent more polar the compound-lower Rf more polar the solvent-higher Rf
know the location of
red phone, fire extinguisher, fire exit, meeting place
SDS binders
safety data sheets
fractional distillation apparatus
separates liquids by characteristic boiling points; used to purify and separate substances in mixtures
Simple + fractional distillation
seperation of miscible liquids Ptotal=Ppentant +Phexane fractional has more theoretical plates and is closer to being ideal than simple
equivalents how to:
smallest reactant mol= 1 larger reactant mol/ smaller reactant mol Ex: NaOH=.28mol HCl= .31mol NaOH= 1 equiv. HCl= 1.11 equiv.
Broken glassware should be disposed of in the
solid waste
Determine the Rf value of a chromatography band.
start = point of application (your dot) solvent front = top of plate where solvent stops substance = pigment
silver nitrate AgNO3
toxic, oxidizing agent, cause skin and eye burns
DCM
volatile and toxic
Dichloromethane (CH2Cl2)
volatile and toxic
suction filtration apparatus
w hirsh funnel
highly polar compounds (like ionic) dissolve in
water
one ___ rule
glove
theoretical yield
(g reactant)x(mol/g reactant)x(equiv of product/equiv of reactant)x(g/mol of product)= yield of product
g to mg
1 g = 1000 mg
SN2 reaction mechanism
1 step forms w methyl ,primary, secondary carbon strong leaving group (Br-, Cl-, I-, etc) strong nucleophile (generally bearing a negative charge) inversion stereochem same # of double/single bonds
E2 reaction mechanism
1 step forms w primary, secondary carbon strong leaving group (Br-, Cl-, I-, etc) strong base (generally bearing a negative charge) more double bonds (pi bonds) as a result
cyclohexene+ pyridinium tribromide->
1,2 bromocyclohexane (one forward, one back)
equiv. ratio of cyclohexene to pyridinium
1:1
SN1 reaction mechanism
2 step forms w secondary or tertiary carbons strong leaving group (Br-, Cl-, I-) Nucleophile can be strong or weak racemization polar solvent only same #of double/single bonds
E1 reaction mechanism
2 step forms w secondary or tertiary carbons strong leaving group (Br-, Cl-, I-) base can be strong or weak racemization polar solvent only more double bonds (pi bonds) as a result
When do you need to fill out an accident report form?
Any time there is an accident - even if the accident is clearly minor.
How to extract a phenol in a water-immiscible solvent
Aqueous hydroxide or carbonate
Adding pyridinium tribromide and observing orange red color, and if some color persists?
Br2 generated, suggests it was cyclohexene limiting reactant
Which of the following resources provide valuable information regarding the University's safety and hazard directions? Select all correct answers.
Chemical Hygiene Plan Hazardous Material Safety Manual
column chromatography
Chromatography in which the substances to be separated are introduced onto the top of a column packed with an adsorbent (as silica gel or alumina), pass through the column at different rates that depend on the affinity of each substance for the adsorbent and for the solvent or solvent mixture, and are usually collected in solution as they pass from the column at different times
BRRRIIINNNNGGGG! The fire alarm starts to ring in the middle of lab. What should you do? Select all correct answers
Follow the directions of your TA, and calmly and quickly evacuate the room and assemble at the steps of Colburn lab Safely stop all experimentation. Leave your personal items. Your safety is more important than your stuff.
fractional distillation if better bc
Fractional distillation leads to a better separation than simple distillation because the glass beads in the fractionating column provide "theoretical plates" on which the vapors can condense and then re-evaporate, and re-condense, essentially distilling the compound many times over.
You are responsible for safety in lab, and should help others stay safe as well. When using a lab coat or gloves, others will always assume that they are contaminated with chemical or biological hazards, so they must be used only for lab work. Which of the following students would you ask to correct their actions? Select all correct answers.
Gabriel has long hair hanging down in front of his face while working in lab Ryan is wearing his goggles on top of his head when working with a chemical. Jackie walks out in the hallway with her gloves still on to take an emergency call.
determining how many theoretical plates:
If a distillation of a mixture is .3 mol fraction in hexanes in benzene provided that was .7 mol fraction hexanes in benzene, how many theoretical planes (using graph) answer 2 (bc it lands directly on .7) tips: if the chart is a negative slope (like the example) move planes to the right, if the slope is positive, move to the left (if the example was .3 mol and .6 mol the answer would be 1-2 planes bc its not directly on .7 where the line ends up)
In addition to Environmental Health and Safety, the following people are allowed to clean-up blood in the lab:
Only Environmental Health and Safety (EHS) is allowed to clean up blood spills in the lab.
TLC plate if you increased the % of ethyl acetate in hexanes (what would happen to Rf)
Rf would become higher due to molecules attracted to polar stationary phase, by dipole-dipole + hydrogen bonds more polar mobile phase = better at disrupting these
Gloves should only be worn when performing lab work. Which activities is it forbidden to do while wearing lab gloves (regardless of how clean you know they are)? Select all correct answers.
Sending a quick text to tell your roommate you won't be leaving lab early today. Making notes of your time point in lab with your own pen.
percent yield
actual yield/theoretical x 100
Bromination of E-stilbene
air condensor allowa for heating without loss of solvent quench filtrate w sodium bisulfite
E1 reaction
alcohol is a bad leaving group- make into -OH2 to make it better
SN1 reaction
alcohol is a poor leaving group protonation makes it a great leaving group
dry organic layer by adding
anhydrous sodium sulfate
water-jacketed condenser
another name for it
Thermocouple
attached to hotplate helps set temperature
on TLC plate orange color signifies
beta-carotene
6 M NaOH
caustic causes burns
hydrochloric acid (HCl)
caustic, cause burns to skin, eyes, respiratory tract
Sulfuric Acid (H2SO4)
caustic, causes chemical burns
on TLC plate dark green color signifies
chlorophyll a
on TLC plate light green color signifies
chlorophyll b
cyclohexanol
combustible liquid, cause skin, eye, respiratory irritation
limiting reactant
comparing theoretical yield of product, smaller number is limiting reactant *limiting reactant is used up first* (Ex: two reactants, one is left in excess in the reaction, this is NOT the limiting reactant)
Clothing
cover waist down
In the permanganate test
determines alkene group by turning a mucky brown precipitate when oxidized (permanganate has a intense purple color) (reaction shows diols)
Steam Distillation of Cloves
distillation of immiscible liquids by adding h2o to high boiling compounds, it will co-distill as a lower temp reaction: cloves, simple distillation, collect disstillate, extract w DCM, dry organic layer w sodium sulfate, rotovap test- KMnO4- positive w 3 compounds Ferric test only positive w eugenol (out of eugenol, eugenol acetate, and caryophyllene)
thermocouple use with
ethylene glycol
everything is dissolved in dichloromethane except molecular sieves, what technique can you use to remove molecular sieves from solution?
filtration (accept gravity or suction)
Ethanol (CH3CH2OH)
flammable
organic compounds
flammable and can cause irritation
glacial acetic acid
flammable, corrosive, cause severe skin and eye burns. lachrymator
Methanol (CH3OH)
flammable, toxic through ingestion, skin contact, inhalation
1-bromobutane
flammable, toxic, irritating
1-butanol
flammable, toxic, irritating
Diethyl Ether (C4H10O)
flammable, volatile (build up pressure in open containers)
chromatography solvent
flammable, volatile, toxic,
No
food and drink
Recrystallization
growing crystals will self select impurites dissolve in min. hot solvent and cool slowly biphenyl dissolves in methal ethyl 4 aminobenzoate dissolve in ethanol benzoic acid dissolve in h2o impurites act as a flaw and make up a lower and broader melting point
If a hazardous chemical has splashed on your clothes, what should you do?
immediately use the safety shower and then begin to remove all affected clothing.
Finkelstein's test
indicates unreacted alkyl chloride or bromide (CHxCl), using NAI/ acetone, SN2 reaction, formation of a precipitate is consistent with the presence of a primary or secondary alkyl halide, but not tertiary.
silica gel
inhalation hazard
more soluble in dichloromethane in water
ionic
Sodium Iodide (NaI)
irritant
sodium bromide NaBr
irritant
amberlyst 15 ion exchange resin
irritant ( especially eyes)
benzoic acid
irritating to the skin, eyes and respiratory system
biphenyl
irritating to the skin, eyes and respiratory system
ethyl 4-aminobenzoate
irritating to the skin, eyes and respiratory system
addition reaction
less double (pi) bonds as a result
labels
name course and lab section date full chemical name
neutral compounds dissolve in
organic solvents (like diethyl ether)
pyridinium tribromide
oxidizing agent, corrosive, causes severe skin and eye burns
ferric chloride test (FeCl3)
phenols (benzene-OH) form intense colors with Iron (III)
goggles
wear at all times
on TLC plate yellow color signifies
xanothophylls