Orgo 1 Lab Final
What is the purification method being used in Experiment 3?
recrystallization
In each of the reactions, which is more water soluble: the starting material or the product? Why?
starting material, Its functional groups H- Bond with water
Vitamin A, vitamin B, and vitamin C are three important biological supplements. Vitamin C is the most water soluble. Vitamin A is the least water soluble. Vitamin B is in between. Which compound is the least polar ________ ? Which compound will have the lowest Rf value ________ ?
vitamin A, vitamin C
How do you know if you can stop adding drying agent to an organic solution?
when it stops clumping
Why is it important to slowly cool the product after recrystallization? A. Allows time for ALL of the product to settle at the bottom B. Allows perfect crystals to form, effectively removing all impurities C. Allows impurities to fully dissolve, since many are more soluble in cold water D. Allows for accurate tracing of temperature, from which we can calculate the lattice energy, and thereby identify the compound
B
Which of the following is/are possible product(s) for reaction 3? A. 1-chloro-2,4-dimethylpentane B. 2-chloro-2,4-dimethylpentane C. 3-chloro-2,4-dimethylpentane D. 1,2-dichloro-2,4-dimethylpentane
B and C
How IR may be used to help estimate the purity of your product (experiment 4)? Select those that apply. A. IR is quantitative - integrate the peaks and compare B. IR is not quantitative - GC would be better for estimation C. The lack of a carbonyl peak around ~1700cm-1 D. The presence of an OH peak
B and D
The region of the of the IR spectrum which contains the most complex vibrations (600-1400 cm-1) is call the . A. thumbprint region B. fingerprint region C. aromatic ring region D. ill-defined region
B.
What is the purpose of using sodium sulfate in the banana oil experiment? A. it is not used B. drying the liquid C. drying the solid D. it is the IR plate
B.
What role does sulfuric acid play in this experiment (5)? Briefly support your answer. A. reactant B. catalyst C. product D. intermediate
B.
Which statement(s) are INCORRECT regarding reflux? A. All of the above. B. 2 of the above C. The boiling point is an important factor when selecting a solvent. D. Reflux is used to overcome large activation energies in organic reactions. E. None of the above. F. A hot water bath always provides sufficient energy to complete the reaction D. Capping the reflux apparatus prevents loss of product.
B. 2 of the above. Both F and D are incorrect
Which of the following outcomes would most possibly occur if you acidified sodium acetylsalicylate to pH 4 instead of pH 2? A. falsely low % recovery of unknown B. falsely low % recovery of aspirin C. falsely high % recovery of aspirin D. falsely low % recovery of sucrose
B. falsely low % recovery of aspirin
In the acid-base reaction from this experiment, what is the conjugate base? A.benzoic acid B. sodium chloride C. sodium benzoate D. hydrochloric acid
B. sodium chloride
Which of the following is used to separate aqueous and organic liquids? A. Buchner funnel B. Separatory flask C. Separatory funnel D. Separation tube
C. Seperatory Funnel
What gas is released when mixing the 5% sodium bicarb solution with the most reflux mixture in experiment 5?
CO2
Which would be a suitable solvent to use for the mobile phase of a normal phase TLC? A. Ethanol B. Dichloromethane C. Water D. Hexane E. 2 of the above
E (both B and D would work)
What issue would you run into if you used pure dichloromethane as your TLC solvent in a reverse phase TLC run? A. Acetic acid would react with the plate B. The plate would float in the acetic acid C. The plate would run fine D. The plate would not develop in iodine E. The plate would not run
E. for reverse phase TLC the stationary phase is non polar and the mobile phase is polar.
Which would be a suitable gas to use for the mobile phase of a reverse phase GC? A. 2 of the above B. Propane C. Helium D. Carbon dioxide E. water vapor
E. for reverse phase you need to use a polar gas and a nonpolar stationary phase
How can compound Y, which has a higher boiling point than compound Z, elute before compound Z in a normal phase GC?
Even though compound Y has a higher boiling point than compound Z, it (compound Y) can elute before compound Z if compound Z has a higher affinity for the column.
In TLC, the Rf value of a compound will decrease the longer the plate resides in the solvent chamber.
False (Rf is a ratio. Therefore, as the solvent travels farther, so does the compound and the ratio will stay constant)
what is the leaving group in reaction 1
H2O
If 1.8 grams of methyl salicylate (MW: 152.15) are used as starting material, how many grams of NaOH (MW: 39.99) must be used to add 2 equivalents?
0.95
Each C=C bond has a contribution toward degree of unsaturation of
1
Each aldehyde function group (-COH) has a contribution of ______ toward degree of unsaturation
1
If you need 8.72 mmol sodium benzoate as a starting material, what mass, in grams, would you add to the reaction.(MW of sodium benzoate is 144.1 g/mol, the density is 1.44 g/mL) Keep three significant figures. Do not include unit since it is asking "in grams" already!
1.26
If you want to make 57 mL of 0.8 M NaOH solution, what mass (in grams) of NaOH would you need to dissolve? Use the molecular weight of NaOH as 40 g/mol
1.82
Calculate the mass of methyl salicylate (MW: 152.15) used if 10.7 mg of salicylic acid (MW: 138.12) are obtained. Assume a 94.3 % yield.
12.5
Calculate the mass of methyl salicylate (MW: 152.15) used if 10.5 mg of salicylic acid (MW: 138.12) are obtained. Assume a 88.2 % yield.
13.1
A molecule has a molecular formula of C7H13O2N. What is the degree of unsaturation of this molecule?
2
How many basic species are there in the intermediate of this reaction (experiment 4)? Assume exactly 2 equivalents of NaOH were used. 5 1 3 4 2
2
How many signals would the above molecule display on a proton NMR spectrum ________ ? What would each signal's integration be __________ ? http://www.chemspider.com/Chemical-Structure.9606923.html
2, 1H, 1H
What is the ideal pH for experiment 4 after adding acid _____ ? Explain what would happen if the acid wasn't added to make the pH in this range _____________.
2, yield would decrease
If 3.8 grams of methyl salicylate (MW: 152.15) are used as starting material, how many grams of NaOH (MW: 39.99) must be used to add 2 equivalents?
2.0
If the solubility of phenacetin is 1.22g/100mL solvent, how much solid (in grams) could be dissolved in 175 mL of solvent?
2.14
You are preparing to begin the Exp. 5 synthesis using 2.28 mL of isopentyl alcohol. Calculate the mmols for this amount of reagent used. You must report moles in mmols. Keep 3 significant figures.
21.1
Between the two compounds, isopentyl acetate and isopentyl alcohol, which compound will elute out first during Normal-Phase Gas Chromatography? A. Isopentyl Acetate B. Isopentyl Alcohol
A
Briefly explain how do you determine if the organic layer is top or bottom with out knowing the density? A. See which layer a drop of water migrates to B. You can't tell. Density is the only way. C. Water is always more dense that organic material and solvents D. Look at the difference in color
A
IR spectroscopy provides valuable information about: A. Functional Groups B. Molecular Weight C. Melting Point D. Conjugation
A
Imagine an organic liquid A has a density of 0.825 g/mL and is mixed with water. Assume this organic liquid does not dissolve in water, then the top layer must be: A. organic B. aqueous
A
Select all that apply: How will IR help us in our analysis to determine if we succeeded in making our product? A. Loss of OH peak B. Presence of halogen peak C. Loss of Halogen peak D. Presence of OH peak
A and B
What is the purpose of "washing" the reaction mixture with dilute NaHCO3? Why does it require more attention than usual to venting? Select all that apply. A. Bicarb makes CO2 B. To remove acid C. Bicarb is explosive D. To remove/extract product
A and B
What change in the IR absorption pattern will tell you that you synthesized Isopentyl Acetate? (Note: Please give both the correct structural features that are present and absent, in relation to the Isopentyl Alcohol) A. Sharp peak at ~1700cm-1 will show carbonyl B. The lack of an OH peak around ~1700cm-1 C. The lack of an OH peak around ~3400 cm-1 D. Broad peak at ~3400cm-1 will show a carbonyl
A and C
Which TWO of the alcohols below would have almost no solubility in room temperature water? (select all that apply) A. octanol B. isopropanol C. cyclopentanol D. butanol
A and C
How could IR spectroscopy be used to distinguish between the following pair of compounds? C6H5CN vs. CH3CH2NH2. Select all that apply: A.Compound 1 has a nitrile peak at 2350 cm-1 B. Compound 1 MUST have aromatic peaks C. Compound 2 would have sp2 hybridized Carbons at >3000 cm-1 D. Compound 2 has a N-H peak at 3300cm-1
A and D
Which reaction(s) have a rate that is determined only by electrophile concentration?
reaction 2 and 3 only
A molecule has a molecular formula of C5H13O2N. What is the degree of unsaturation of this molecule?
0
Each alcohol function group (-OH) has a contribution of ________ toward degree of unsaturation.
0
If the solubility of phenacetin is 1.22g/100mL solvent, how much solid (in grams) could be dissolved in 44 mL of solvent? Answers should be given to TWO decimal places. Do NOT include unit.
0.54
If you want to make 48 mL of 0.4 M NaOH solution, what mass (in grams) of NaOH would you need to dissolve? Use the molecular weight of NaOH as 40 g/mol *DO NOT include units in answer. Answer to 2 decimal places.
0.77
Assuming the reaction goes to completion, what is the theoretical yield, in grams, of benzoic acid (in grams) when using 1.36 grams of sodium benzoate? (MW of sodium benzoate is 144.1 g/mol, MW of benzoic acid is 122.1 g/mol)
1.15
How many equivalent groups of hydrogen are there in the ortho- structure given? (scroll down a bit) https://2012books.lardbucket.org/books/principles-of-general-chemistry-v1.0/s28-01-functional-groups-and-classes-.html
3
Based on the structure of cytosine, what is its degree of unsaturation? http://www.biology-pages.info/B/BasePairing.html
4
Based on the structure of thymine, what is its degree of unsaturation? http://www.biology-pages.info/B/BasePairing.html
4
How many equivalent groups of hydrogen are there in 2-methylbutane? http://www.compoundchem.com/wp-content/uploads/2015/08/A-Basic-Guide-to-Decoding-the-Names-of-Organic-Compounds.png
4
You are preparing to begin the Exp. 5 synthesis using 8.08 mL of isopentyl alcohol. Calculate the mmols for this amount of reagent used. You must report moles in mmols. Keep 3 significant figures.
74.7
The following table shows data for a sample that was run under normal phase GC conditions: Peak Ret.Time PeakArea Peak 1 1.15 min 105 cm^2 Peak 2 3.5 min 60 cm ^2 Peak 3 5.0 min 75 cm^2 What is the percent composition of the least polar species? Answer to 2 decimal places. The running gas is not reported as a peak.
43.75
The following table shows data for a sample that was run under normal phase GC conditions: Peak Ret.Time PeakArea Peak 1 1.15 min 105 cm2 Peak 2 3.5 min 60 cm2 Peak 3 5.0 min 75 cm2 What is the percent composition of the least polar species? Answer to 2 decimal places. The running gas is not reported as a peak.
43.75
During Gas Chromatography you observe three peaks. These peaks have measured areas of 18 cm2, 67 cm2, and 53 cm2, respectively in the order. What is the percent composition of Isopentyl Acetate in your sample? You need to know which peak is your isopentyl acetate first! Keep 3 sig figs. Report as percentage but leave "%" out!! Warning: one peak is actually due to your solvent acetone used in washinng the syringe. It should not be included in your % composition calculation. You need to know which peak is due to acetone as well.
55.8
If you have 2.6g of an unknown, how much boiling water is needed to dissolve that substance? (solub. b.w. of unknown is 0.046 g/mL; density of water is 1.00 g/mL).
56.5 mL
http://www.mhhe.com/physsci/chemistry/carey/student/olc/graphics/carey04oc/ch13/figures/hisp04.gif The 1H NMR spectrum above represents a molecule that contains only carbon and hydrogen atoms. If the degree of unsaturation is equal to 2, how many carbon atoms are there?
6
During Gas Chromatography you observe three peaks. These peaks have measured areas of 27 cm2, 63 cm2, and 33 cm2, respectively in the order. What is the percent composition of Isopentyl Acetate in your sample? You need to know which peak is your isopentyl acetate first! Keep 3 sig figs. Report as percentage but leave "%" out!! Warning: one peak is actually due to your solvent acetone used in washinng the syringe. It should not be included in your % composition calculation. You need to know which peak is due to acetone as well.
65.6
If reaction one began with 4.8 g of alcohol starting material and you decide to use 2 equivalents of sodium bromide, how many grams of NaBr would you need? (NaBr molar mass=102.89 g/mol; SM molar mass=136.09g/mol)
7.26
On your first go, you decide to reflux, wash and separate. To check what you have made, you run a quick IR, which you think suggests that you have a mixture of starting material and product, so you decide to purify by distillation. The product you obtain is much purer, but you note you have a very low yield and not enough to run an HNMR sample. What is the most important thing you should change experimentally for next week? A. dry with sodium sulfate before distilling B. use more starting material in the intial reaction C. increase the equivalents of halogen from 2.5 to 3 D. reflux at a higher temperature
A
What results when too much solvent is used to dissolve the product in recrystallization? A.Product loss - too much solvent dissolves more product B. Improper/incomplete recrystallization - more solvent-solvent interactions do not allow for complete dissociation of the product C.The melting point range raises and becomes more narrow D. Falsely high percent recovery - extra solvent is contributing to mass
A
What salt is used to complex water molecules in attempts to remove them from an organic solution? A. sodium sulfate B. potassium permanganate D. sodium phosphate E. sodium hydroxide
A
Which of the following compounds has an IR absorption at 1640 cm-1? A. 1-pentene B. CH3CH2C=OCH2C3 C.pentane D. propyl acetate
A
Why do we use wavenumbers (cm-1) instead of wavelength on the x-axis of the IR spectrum? A. wavenumber is directly proportional to energy B. wavenumbers correspond to the length of the bond C. wavenumber is inversely related to energy D. The numbers are really small and interpretable
A
Why is the water wash after finishing the heat under reflux procedural step so important? A. It dilutes the acid B. it recrystallizes product C. it dilutes the sodium bicarbonate D. it provides better IR reads
A
Which of the following compounds has the most deshielded protons? A. Chloromethane B. Methane C. Iodomethane D. Bromomethane
A (chlorine is more electronegative than Bromine and Iodine)
As in part B of exp. 1, when the graphs are made properly, the density of the liquid can be obtained via: A.Slope B. y-intercept C.R-square
A (mass on the y-axis and volume on the x-axis)
When recrystallizing, it is important to have an appropriate solvent. Select all that are characteristics of a good solvent. A. Completely dissolves impurities B. When hot, the solvent dissolves a large amount of the compound C. Is volatile enough that crystallized solid can be dried D. Boils above the compounds melting point E. Partially dissolves impurities F. Does not react chemically with the compound G. When cold, the solvent dissolves a large amount of the compound H. Inexpensive
A, B, C, F, H
What ingredient of Panacetin is the most acidic and most easily ionizable in the presence of a base? A. Acetylsalicylic acid B. Sodium acetylsalicylate C. Panacetin D. Sucrose
A.
If toluene has a density of 0.867 g/mL and was used in an extraction with an aqueous solution, which would be the bottom layer in the separatory funnel? A. Aqueous B. Organic
A. Aqueous
Which is a more stable conjugate base? A. sodium chloride B. sodium benzoate
A. because it is the conjugate base of a strong acid
Imagine an organic liquid A has a density of 0.825 g/mL and liquid B has a density of 1.045 g/mL. If the two liquids were mixed (but are immiscible), which liquid would be on bottom? A. liquid B B. liquid A
A. liquid B
The following data was collected from a TLC plate for 4 different compounds. The distance's traveled by each is shown below: Spot A: 8.2 cm Spot B: 0.7 cm Spot C: 6.5 cm Spot D: 1.3 cm The spotting line was placed 1.5 cm above the base and the solvent traveled 10.5 cm from the bottom of the plate. Calculate the Rf value for each compound. (0.5 point each)
A=0.911 B=0.078 C=0.722 D=0.144
Acetaminophen is the chemical name of what common drug? A. Ibuprofen B. Tylenol C. Aleve D. Morphine
B
HA and HB are two acids and A- is a more stable conjugate base than B-. We can conclude that: A. The acidity of HA and HB are comparable B. HA is a stronger acid than HB C. HB is a stronger acid than HA
B
If a student added HCl(aq) to sodium benzoate and stopped around pH 3 (instead of 2 as described in the lab procedure), how would this affect the % yield of this experiment? A. Higher % yield B. Lower % yield C. This change will impact % purity more than % yield
B
This unit identifies the strength of an organic acid comparatively versus other organic acids. A. pH B. pKa C. [H+]
B
Which compound would be expected to show intense IR absorption at 2352cm-1? A. CH3COOH B. C6H5CN C. Prop-1-ene D. CH3CH2SCH3
B
Which of the following is mostly insoluble in water? A.Sodium benzoate B. Benzoic acid C. Sodium chloride D. Hydrochloric acid
B
Which of the following is the rate law for the reaction 3 mechanism? A. rate = k[nucleophile] B. rate = k[alkyl halide] C. rate = k[alkyl halide][nucleophile] D. rate= k[nucleophile]^2
B
The following link shows a sample normal phase TLC plate: Rank the compounds in increasing polarity. Blue is above green which is above red
Blue (least polar), green, red (most polar)
Drawing arrows to explain electron movement in organic chemistry is known as a (an): A. dissociation B. reaction diagram C. mechanism D. equilibrium
C
H2SO4 is a stronger acid than HCl. If H2SO4 is used to adjust the pH to 2, instead of HCl, how will this change affect the experimental result? A. There will be significantly less benzoic acid produced B. There will be significant more benzoic acid produced C. The amount of benzoic acid produced will not be significantly different
C
What is one way to identify a compound using instrumental analysis? A. melting point B. boiling point C. NMR D. density E. color
C
What would happen if the spotting line was below the solvent line in the chamber? A. The plate would dissolve B. It give a more precise Rf value C. The spot would dissolve and run poorly D. The plate would run as normal
C
While running an experiment, you are rushed for time and forget to dry your product. All methods of analysis indicate that no alcohol containing compounds were made. However, when you check using IR, you notice a broad absorption around 3200-3500 cm-1. If there is no alcohol, why is there still this absorption this region? Select all that apply. A. The other spectra analyses are inaccurate B. A high amount of sp3 hybridized carbons causes the peak to shift to this region C. There is water in the sample D. The salt plate also absorbs in the 3200-3500 region
C
Why would we use water as a solvent instead of dichloromethane (DCM) in experiment 4? A. Water will dissolve the product and it will be ideal to separate B. DCM boils at a low temperature all of it would evaporate and your rxn would scortch C. DCM boils at a low temperature, the reaction needs to have the maximum energy input D. water is not reactive, DCM is
C
From the lecture, which one of the following is not one of the five basic categories of organic lab work? A.analysis B.organic reaction C.heating D. separation
C (5 categories are RRSPA-research, reaction, separation, purification, analysis)
How would IR spectroscopy be used to quickly analyze the correct formation of product in experiment 4? (select all that apply) A. A new aromatic peak will show up for product B. Loss of OH group peak C. Loss of Ester peak D. Gain of Carboxylic acid peak
C and D
what are some disadvantages of using recrystallization (select all that apply) A. it is expensive B. it is time consuming C. products are always somewhat soluble-product loss is inevitable D. identifying a proper solvent is difficult
C and D
How could IR spectroscopy be used to distinguish between the following pair of compounds? C6H6 (benzene) vs. C6H12 (cyclohexane)? Select all that apply. A. Compound 1 would have sp2 C-H less than 3000cm-1 B. Compound 1 would have a smaller fingerprint region because of less hydrogens C. Compound 2 would have sp3 C-H less than 3000cm-1 D. Compound 2 would have peaks indicative of an aromatic system E. Compound 1 would have sp2 C-H greater than 3000cm-1 F. Compound 2 would have sp3 C-H greater than 3000cm-1
C and E
Give 2 reasons or indications that the reaction from experiment 4 was successful. These should be empirical observations immediately obtainable after reflux, not from instrumental analysis. (select all that apply) A. A solid is formed after reflux B. It smells like wintergreen oil C. It no longer smells like wintergreen oil D. IR analysis shows a carboxylic acid E. A solid is formed after acid addition F. The reflux mixture evaporates G. The reflux mixture is cloudy H. MP Range is good
C, E
If an impurity exists in a sample, the melting point _________ and ________. A. raises and broadens B. lowers and narrows C. lowers and broadens D raises and narrows
C.
Acetic acid is a weak acid. When acetic acid dissolves in water to make a solution, what is the major form of acid in the solution? A. acetate ion B. hydronium ion C. hydroxide ion D. acetic acid E. water
D
Explain why it is important to use pencil when drawing your spotting line on the TLC plate? A. Pencil markings run up the plate B. Pencil marks are not visible after iodine C. Pencil markings are more visible after being exposed to the iodine D. Pencil markings do not run up the plate
D
In Exp. 1, what is the most notable observable physical trait of the chemical reaction that signals its progress toward the product? A. change in temperature B. change in volume C. change in color D. change in state of matter
D
In the acid-base reaction from this experiment, what is the Bronsted acid? A. sodium chloride B. benzoic acid C. sodium benzoate D hydrochloric acid
D
The IR spectrum of a sample contains absorptions at 3050, 2950, and 1620 cm-1. To what class of organic compound does this sample most likely belong? A. Alkane B. Alcohol C. Ester D. Alkene E. Alkyne
D
Which compound would be expected to show intense IR absorption at both 3500 and 1733cm-1? A.ethanol B. CH3CH2C=OCH2C3 C. pyridine D. 2-hydroxypropanol
D
Which of the following outcomes would most possibly occur if you initially dissolved the panacetin mixture in a more polar organic solvent, still immiscible in water, instead of dichloromethane? A. falsely low % recovery of aspirin B. falsely low % recovery of unknown C. falsely high % recovery of sucrose D. falsely low % recovery of sucrose
D
Name two pieces of equipment essential for carrying out vacuum filtration A. short-stem funnel B. Erlenmeyer flask C. beaker D. Buchner funnel E. side-arm flask
D and E
During your melting point analysis of salicylic acid, you observe a melting point range from 130 C-159 C. Does this represent pure product? Why or why not? Choose the best answers A. No, the value is far from literature B. Yes, the maximum value is close to literature C. Yes, the range is narrow D. No, the range is too broad
D.
which mechanism does reaction 2 favor?
Sn1
what mechanism does reaction 1 favor?
Sn2
Which reaction(s) have a rate that is determined by both the nucleophile and electrophile concentration?
reaction 1 only
Which would be more soluble in water, Compound A (has an ester and a carboxylic acid) or Compound B (has a ketone)? Why?
compound A because it has more locations for H-bond interactions, therefore is ti more soluble in water
In this experiment (3), how are you determining the identity of the unknown?
melting point
What is the splitting of the 2nd carbon (one that has a double bond and a methyl) on 4-ethyl-2-methylhex-1-ene?
octet
If methylene chloride has a density of 1.34 g/mL and was used in an extraction with an aqueous solution, which would be the bottom layer in the separatory funnel?
organic