chm2211l: final exam study guide

b) soap

practice lab exam: ______ is often formed as an undesired by-product during the reaction that produces biodiesel. a) glyceraldehyde b) soap c) ethylene glycol d) none of these

a) true

practice lab exam: all compounds that act as dyes contain a chromophore. a) true b) false

c) 10.4 g

practice lab exam: if 100 g of oleic acid triglyceride (885.4 g/mol) is converted to oleic acid methyl ester (296.5 g/mol) using excess methanol and KOH according to the equation below. how many grams of glycerin (92.1 g/mol) byproduct are formed? a) 104 g b) 35 gc c) 10.4 g d) 31 g

b) 1.81 grams

practice lab exam: if the reaction was conducted using 3.25 grams of 4-chlorobenzaldehyde, what is the theoretical yield of 4-chlorobenzoic acid (in grams)? a) 1.46 grams b) 1.81 grams c) 2.92 grams d) 3.62 grams

a) true

practice lab exam: the purpose of using a trap during vacuum filtration is to catch any overflowing filtrate before it can enterthe house vacuum system. a) true b) false

C. 3-hexanol

spectroscopy quiz: which molecule is most likely represented by the IR spectrum shown here (attached)? A. hexanoic acid B. 2-hexene C. 3-hexanol D. hexane

B. 250 nanometers

spectroscopy quiz: which of the following wavelengths of light is the highest in energy? A. 400 micrometers B. 250 nanometers C. 450 nanometers D. 3 centimeters

B. C=O

spectroscopy quiz: without doing a calculation, which of the bonds below would you expect to have the higher stretching frequency? A. C-O B. C=O

53.5

KC #1: you conducted your amide synthesis of acetophenetidin starting with 8.37 g p-phenetidine (137.18 g/mol), and you isolated 5.85 g of acetophenetidin (179.22 g/mol) at the end of the reaction. assuming that p-phenetidine was the limiting reagent, what is the percent yield for this reaction? report your answer to one decimal place (i.e., 78.4).

B. to remove residual water from organic solvent

KC #2: what is the purpose of MgSO4 that is used in an acid/base extraction experiment? A. to remove remaining organic solvent from aqueous layer B. to remove residual water from organic solvent C. none of these D. more than one of these E. to lower the vapor pressure of the organic solvent

b) use some of the reaction solvent to transfer the product into the Büchner funnel

practice lab exam: What should you do if some of your product still remains in the reaction flask when you are trying to collectit via vacuum filtration? a) dissolve the product, and pour the solution into the Büchner funnel b) use some of the reaction solvent to transfer the product into the Büchner funnel c) dissolve the product, and pour the solution into the liquid waste d) wait for the product to be mostly dry, and then scrape it into the solid waste e) dispose of the flask in the solid waste and obtain a replacement from the stockroom

c)

practice lab exam: a 1H NMR spectrum of an organic molecule showed two signals: a triplet and a quartet. Which of the molecules shown would exhibit this splitting pattern? a) b) c) d) e) more than one of these

d) 85%

practice lab exam: a student carried out an organic synthesis and obtained 2.63 grams of crude product. the student decidedto recrystallize 1.50 grams of the product, and they recovered 1.28 grams of pure material. what is the percent recovery for the recrystallization? a) 49% b) 57% c) 74% d) 85% e) 90%

b) 2.74 g

practice lab exam: a student reacted 1.43 grams of salicylamide (137.14 g/mol) and 1.72 grams of sodium iodide (149.89g/mol) to produce iodosalicylamide (263.03 g/mol). calculate the theoretical yield for this transformation. a) 2.51 g b) 2.74 g c) 3.02 g d) 3.15 g e) 3.30 g

c) 4.8 mL of solvent A and 3.2 mL of solvent B

practice lab exam: a student was asked to prepare 8 mL of a 6:4 eluent solution of solvent A: solvent B for their TLC developing chamber. what volumes of solvent A and solvent B are needed to prepare the requested eluent mixture? a) 4.4 mL of solvent A and 3.6 mL of solvent B b) 4.4 mL of solvent A and 2.9 mL of solvent B c) 4.8 mL of solvent A and 3.2 mL of solvent B d) 5.4 mL of solvent A and 2.6 mL of solvent B

b) the reaction is not yet completed since there is unreacted starting material present

practice lab exam: a student was carrying out a reaction in the organic lab. at a point during the reaction, the reaction mixture (R) was spotted on a TLC plate along with a reference of the starting material (S) which is the limiting reagent. the plate was then eluted with 60:40 hexane/ethyl acetate. what can you conclude about the reaction from the TLC results shown here? a) the reaction is complete, and there are two products formed b) the reaction is not yet completed since there is unreacted starting material present c) the product of the reaction is more polar than the starting material d) both (b) and (c) are correct e) None of these statements are correct

b) higher MW than expected

practice lab exam: a student was setting up a block copolymer reaction, and while he was transferring the reactants to the vial, he dropped a small amount of the initiator on the benchtop. how will this impact the molecular weight of the polymer that is formed? a) lower MW than expected b) higher MW than expected c) no impact on molecular weight

c) 3

practice lab exam: a student's notebook entry is given below for the synthesis of nylon 10,6 that was done during the polymers lab. consider the underlined statements, and indicate how many of these statements are incorrect. "the Nylon-10,6 is a polyester polymer which was synthesized from sebacoyl chloride and hexamethylene diamine as shown above. this is an example of a condensation polymerization where water was obtained as the byproduct. the product (nylon-10,6) was readily soluble inorganic solvents such as toluene and acetone." a) 1 b) 2 c) 3 d) 4 e) no incorrect statement

b) the carboxylic acid will have a signal at about 1730 cm-1 but the alcohol will not.

practice lab exam: after completing the reaction and isolating both products, you went out for a lunch break but you were so hungry that you forgot to label the products before you left the lab. how can you tell them apart using IR spectroscopy? a) the alcohol product will show a signal at about 3500 cm-1 but the carboxylic acid will not. b) the carboxylic acid will have a signal at about 1730 cm-1 but the alcohol will not. c) it isn't possible to distinguish these molecules using IR alone.

a) (4-chlorophenyl)methanol

practice lab exam: after the reaction is complete, the product mixture is dissolved in ether and extracted with two portions of sodium bicarbonate solution. which compound remains in the ether layer after this extraction? a) (4-chlorophenyl)methanol b) 4-chlorobenzoic acid

b)

practice lab exam: assume that you dissolved a mixture of benzoic acid and phenol in diethyl ether, and then extracted withaqueous NaHCO3. which equation represents the species present after this extraction? a) b) c)

d) both (a) and (b)

practice lab exam: changing the moles of which of the following will affect the number of repeat units in a chain addition polymer? a) initiator b) monomer c) catalyst d) both (a) and (b) e) all of these

c) the Rf value of both A and B will decrease

practice lab exam: consider a sample comprised of two components A and B. when the sample was spotted on a TLC plate and eluted using 50:50 of hexane/ethyl acetate, the results were as shown below. if you made a new TLC plate of the same sample and eluted with 70:30 of hexane/ethyl acetate, what change in Rf values would you expect to see? a) the Rf values of both A and B will remain the same b) the Rf value of both A and B will increase c) the Rf value of both A and B will decrease d) the Rf value of A will decrease, while the Rf value of B will increase e) the Rf value of A will increase, while the Rf value of B will decrease

b) 3.54 g

practice lab exam: consider the formation of the coumarin derivative shown below. If you wanted to make 4.75 grams of product, how many grams of 4-(diethylamino)salicylaldehyde should be used? a) 2.38 g b) 3.54 g c) 6.37 g d) 7.05 g e) none of these

a. true

practice lab exam: ethanol is formed during the cyclization reaction shown here: a. true b. false

d) all of the above

practice lab exam: how could 1H NMR distinguish between 1-Butanal and 2-Butanone? a) 4 signals are expected for 1-Butanal and 3 signals are expected for 2-Butanone b) 1-Butanal is expected to have one signal that has an integration value of 1, but 2-Butanone will not. c) 1-Butanal is expected to have a sextet but 2-Butanone will not d) all of the above e) aldehydes and ketones cannot be distinguished by 1H NMR

d) neutralize with dilute acid, then collect product using vacuum filtration.

practice lab exam: how would you collect the product contained in the aqueous layer after the extraction? a) dry with anhydrous magnesium sulfate, decant, and evaporate under reduced pressure. b) neutralize with dilute acid, then evaporate under reduced pressure. c) neutralize with sodium hydroxide, then collect product using vacuum filtration. d) neutralize with dilute acid, then collect product using vacuum filtration.

a) 9

practice lab exam: letícia and her group are trying to determine the distribution coefficient as part of their extraction lab. they dissolved 1.50 grams of benzoic acid in 75 mL of water and used 75 mL of diethyl ether to extract it. after the extraction was completed, letícia noted they'd been able to extract 1.35 grams. what is their distribution coefficient? recall that Kd = (concentration in organic phase)/(concentration in aqueous phase). a) 9 b) 0.1 c) 0.9 d) 1.1

C. plate C

practice lab exam: plate X represents the TLC of a compound that was separated using a 70:30 hexane/ethyl acetate mixture. which plate corresponds to the results that would be observed on a longer plate, using the same solvent mixture? A. plate A B. plate B C. plate C D. no way to predict

b)

practice lab exam: reaction progress can be monitored by TLC. which TLC plate would indicate the reaction is complete? a) b) c) d)

b) false

practice lab exam: safety glasses are no longer required in the lab once a student finishes an experiment and locks their drawer. a) true b) false

b) transesterification

practice lab exam: the chemical transformation involving the conversion of vegetable oil into biodiesel can be called: a) saponification b) transesterification c) hydrolysis d) gasification e) None of the above

b) sample A is less pure than sample B.

practice lab exam: two students synthesized aspirin (lit. m.p. = 135°C) and measured melting points of their samples: student A recorded 131-135°C and student B recorded 133-134°C. which statement is correct about these samples? a) sample A is more pure than sample B b) sample A is less pure than sample B. c) both samples are equally pure. d) purity cannot be determined using melting point

d) all of the above

practice lab exam: what type of chemical interaction(s) will cause a dye to adhere to a piece of fabric? a) vander Waals attractions b) hydrogen bonding c) covalent bonding d) all of the above

a) electrophilic aromatic substitution

practice lab exam: what type of organic reaction is the aryl diazonium coupling shown below? a) electrophilic aromatic substitution b) nucleophilic aromatic substitution c) e2 elimination d) sn1 substitution e) sn2 substitution

a) acid

practice lab exam: what was the role of Dowex 50WX4 beads in the coumarin synthesis? a) acid b) base c) drying agent d) nucleophile

e) the solvent in the organic phase has a density less than 1 g/mL

practice lab exam: when aqueous 2 M HCl is added to an organic phase inside a separatory funnel, a new layer forms at thebottom of the funnel as the organic phase rises to the top. which of the following can be concluded basedon this observation? a) most of the major product is present in the aqueous layer b) most of the major product is present in the organic layer c) the solvent in the organic phase has a density greater than 1 g/mL d) the concentration of the aqueous phase is less than the concentration of the organic phase e) the solvent in the organic phase has a density less than 1 g/mL

b) when you see the first drop of liquid in the capillary

practice lab exam: when do you record the first temperature within the melting point range of a sample? a) when the sample starts to compress b) when you see the first drop of liquid in the capillary c) when the entire sample in the capillary is a liquid d) when you press start on the instrument

c) the amount of initiator determines the number of repeat units in the polymer

practice lab exam: when performing a polymerization, why is it important to know the exact amount of initiator used? a) the initiator is highly reactive and can dimerize if used in excess. b) when too much initiator is used, the molecular weight of the polymer will be higher than expected. c) the amount of initiator determines the number repeat units in the polymer. d) the initiator requires a catalyst to react.

d.

practice lab exam: which of the following is not a valid resonance structure for 4-(diethylamino)salicylaldehyde (shown at the right): a. b. c. d.

4,4-dimethyl-2-pentanone

spectroscopy quiz: a compound with the molecular formula C7H14O gives the proton NMR spectrum shown below. an IR of this same compound shows a strong signal at 1720 cm-1. based on this information, determine the structure of this molecule. what is the IUPAC name of the molecule? remember to report the answer with proper notation. the IUPAC name is _______________ .

4

spectroscopy quiz: dopamine, C8H11NO2, has ____________ degrees of unsaturation.

C. 3

spectroscopy quiz: how many proton NMR signals will be observed for the molecule shown below? A. 2 B. 4 C. 3 D. 5

B. false

spectroscopy quiz: true or false: light with a higher frequency will have a longer wavelength. A. true B. false

C. quartet

spectroscopy quiz: what is the splitting pattern for the underlined protons in the molecule shown? A. doublet B. singlet C. quartet D. triplet

B. 1-hexene

spectroscopy quiz: which of the molecules listed below is most likely to give this IR spectrum (attached)? A. 2,3-dimethyl-2-butene B. 1-hexene C. hexane

C. methyl propionate

spectroscopy quiz: which of these esters would give the proton NMR spectrum shown? A. ethyl acetate B. propyl formate C. methyl propionate

A. Scratch the bottom of the beaker B. Evaporate solvent to concentrate solution D. Cool the solution in an ice bath

KC #2 Chloe tried to purify the crude product obtained from the synthesis of iodosalicylamide through recrystallization by using 95% ethanol as a solvent. After cooling the solution at room temperature, Chloe notices there is still no crystal formation. What could Chloe do? Choose all that apply. A. Scratch the bottom of the beaker B. Evaporate solvent to concentrate solution C. Add more ethanol to the solution D. Cool the solution in an ice bath E. Add seed crystals of salicylamide

B. water

KC #2 assume that an extraction has been carried out using water and diethyl ether, similar to the Kd experiment in the lab, as illustrated with the separatory funnel drawn below. chose the correct answers from the drop-down menus: the solvent in the bottom layer will be: A. diethyl ether B. water C. not possible to determine

A. diethyl ether

KC #2 assume that an extraction has been carried out using water and diethyl ether, similar to the Kd experiment in the lab, as illustrated with the separatory funnel drawn below. chose the correct answers from the drop-down menus: the solvent in the top layer will be: A. diethyl ether B. water C. not possible to determine

doublet

KC #2 consider the molecule shown below, and use the dropdown menus to indicate the expected splitting patterns for the indicated protons. what is the splitting pattern of the protons labeled a?

quartet

KC #2 consider the molecule shown below, and use the dropdown menus to indicate the expected splitting patterns for the indicated protons. what is the splitting pattern of the protons labeled b?

triplet

KC #2 consider the molecule shown below, and use the dropdown menus to indicate the expected splitting patterns for the indicated protons. what is the splitting pattern of the protons labeled c?

singlet

KC #2 consider the molecule shown below, and use the dropdown menus to indicate the expected splitting patterns for the indicated protons. what is the splitting pattern of the protons labeled d?

4

KC #2 how many signals would you expect to see in the 1H NMR of the following compound?

0.4

KC #2 you were asked to dissolve 9.2 g of compound A in 60 ml of water. after single extraction with 60 ml ether, you recovered 2.65 g of compound A from the ether layer. calculate the Kd value for the compound A in ether/water system. report your answer to 2 decimal places (i.e., 0.01). recall that Kd = concentration in organic phase / concentration in aqueous phase

B. sodium hydroxide is too strong of a base and will deprotonate both compounds

KC #2: a student set up an extraction to separate benzoic acid and phenol using diethyl ether, deionized water and sodium hydroxide. The student completed the extraction but did not get the desired results. What went wrong? A. it is not possible to separate the two compounds using extraction B. sodium hydroxide is too strong of a base and will deprotonate both compounds C. deionized water and diethyl ether are miscible D. sodium hydroxide is too weak of a base and will not deprotonate either of the compounds

b. false

KC #2: more product can be obtained from a single extraction with a large volume rather than with multiple extractions with smaller volumes. a. true b. false

d. go ahead and use the funnel - you will be adding aqueous solutions anyway

KC #2: you need to use your separatory funnel for an extraction, but you notice that there is some residual water in it from when it was washed during the previous lab period. what should you do? a. use a paper towel to dry the inside of the funnel prior to using it again b. borrow a lab mate's funnel and wait for yours to dry c. take the funnel to the stockroom and ask to exchange it d. go ahead and use the funnel - you will be adding aqueous solutions anyway

A. by running a TLC and checking the number of spots that appear on the TLC plate. more than one spot would indicate the presence of other additives. C. by taking an NMR of the drug to confirm its identity and purity. D. by taking the melting point of the drug and comparing it to the melting point of acetaminophen from the literature.

KC #3 after consuming an over the counter (OTC) non-prescription drug, one of your lab mates starts to experience some unpleasant side effects that could be due to allergic reactions. the bottle label says that the drug contains acetaminophen only with no other additives. how could you verify this statement in the laboratory? select all that apply. A. by running a TLC and checking the number of spots that appear on the TLC plate. more than one spot would indicate the presence of other additives. B. it's not possible to determine the presence of additives. the drug will have to be sent to a toxicological laboratory for a complete analysis. C. by taking an NMR of the drug to confirm its identity and purity. D. by taking the melting point of the drug and comparing it to the melting point of acetaminophen from the literature. E. by consuming some of the drugs to see if you experience similar side effects.

A. trace amounts of water in the system cause hydrolysis as a side reaction

KC #3 one of the major side products in the biodiesel experiment is the formation of soap. why do we see the formation of soap? A. trace amounts of water in the system cause hydrolysis as a side reaction. B. all of these reasons will contribute to soap formation. C. even very clean glassware contains some residual soap, so that ends up in our biodiesel product. D. excess methanol causes the formation of soap.

17.23

KC #3 the formation of biodiesel is achieved by reacting a triglyceride with excess alcohol. suppose you are performing a synthesis of biodiesel from a triglyceride (MW: 343 g/mol, density: 1.24 g/mL) as shown below. if you start the reaction with 39.27 mL of the triglyceride, what is the minimum amount (in mL) of methanol (MW:32.04 g/mol, density: 0.792 g/mL) that should be used to complete the reaction? NOTE: the reaction below is not balanced - be sure to consider correct stoichiometry in your calculation. report your answer to two decimal places.

A. tetrahydroborate ions cause crosslinking of poly(vinyl alcohol) chains by hydrogen bonding

KC #3 which statement best describes the formation of the slime polymer? A. tetrahydroborate ions cause crosslinking of poly(vinyl alcohol) chains by hydrogen bonding B. borax causes oxidation of the poly(vinyl alcohol) chains which leads to crosslinking C. poly(vinyl alcohol) is a non-Newtonian fluid and undergoes thickening when stirred D. none of these are correct

0.53

KC #3 you conducted a TLC experiment and found that your compound traveled 5.02 cm and the eluting solvent traveled 9.51 cm. what is the Rf value for your compound? report your answer to two decimal places (i.e., 0.01).

A. more polar

KC #3: a student conducted an organic reaction where 1 mole of compound A was reacted with 1 mole of compound B. the TLC plate below was spotted with compound A, compound B, and a sample from the reaction mixture (rxn mix) and shows the results after eluting with 50/50 ethyl acetate/hexane. given these results, use the dropdowns below to answer the following questions: consider the lane that shows the reaction mixture. are the starting materials more or less polar than the reaction product? A. more polar B. less polar

C. 0.27

KC #3: a student conducted an organic reaction where 1 mole of compound A was reacted with 1 mole of compound B. the TLC plate below was spotted with compound A, compound B, and a sample from the reaction mixture (rxn mix) and shows the results after eluting with 50/50 ethyl acetate/hexane. given these results, use the dropdowns below to answer the following questions: what is the Rf value for Compound B? A. 1.49 B. 3.72 C. 0.27 D. 0.50 E. 0.20 F. 0.67

A. compound a

KC #3: a student conducted an organic reaction where 1 mole of compound A was reacted with 1 mole of compound B. the TLC plate below was spotted with compound A, compound B, and a sample from the reaction mixture (rxn mix) and shows the results after eluting with 50/50 ethyl acetate/hexane. given these results, use the dropdowns below to answer the following questions: which compound, A or B, was the limiting reagent in this reaction? A. compound a B. compound b C. there is no limiting reagent in this reaction

B. geraniol

KC #3: the two compounds shown below, limonene and geraniol, are essential oils that are found in citrus fruits like oranges and lemons. if you did thin layer chromatography (TLC) on a mixture of limonene and geraniol, which compound would have the smaller Rf value? A. limonene B. geraniol

A. true

KC #1: inaccurate melting point determinations are often made due to poor heat transfer to the sample. A. true B. false

55.58

KC #1: assume that you carried out a recrystallization of ibuprofen using ethanol. if you started with 5.11 grams of crude ibuprofen and isolated 2.84 grams of pure ibuprofen, what is your percent recovery? report your answer to the nearest 0.01%.

buchner funnel

KC #1: match the items in the filtration apparatus below with their name/function. what is item a?

filter flask

KC #1: match the items in the filtration apparatus below with their name/function. what is item b?

pinch clamp to control vacuum

KC #1: match the items in the filtration apparatus below with their name/function. what is item c?

hose connector to lab vacuum

KC #1: match the items in the filtration apparatus below with their name/function. what is item d?

C. two compounds that have different melting point ranges must be different compounds. D. the melting point of a substance is same as its freezing point.

KC #1: select all the following options that are true about the melting point experiment. A. melting point of a compound does not depend on its purity B. if the two compounds have the same melting point range, we can confirm that they are identical without any further experimentation C. two compounds that have different melting point ranges must be different compounds. D. the melting point of a substance is same as its freezing point.

b. false

KC #1: when choosing a recrystallization solvent, you want to use a solvent in which both the product and impurities are highly soluble at all temperatures. a. true b. false

A. the product is soluble at elevated (boiling point) temperatures B. the solution is allowed to cool slowly to room temperature, followed by cooling in an ice bath D. the product is insoluble at cool temperatures

KC #1: when conducting a recrystallization, ideally (check all that apply): A. the product is soluble at elevated (boiling point) temperatures B. the solution is allowed to cool slowly to room temperature, followed by cooling in an ice bath C. the impurities remain insoluble, even when cooled D. the product is insoluble at cool temperatures

D. repeat the hot gravity filtration using a clean funnel a new piece of filter paper

KC #1: you are conducting the acetophenetidin reaction and just finished your hot gravity filtration. you notice that you have some activated carbon in your filtrate solution. what is the best way to address this problem? A. just leave the activated carbon in the filtrate because it will dissolve during the recrystallization of your product B. there is no way to correct for this result, so the only choice is to start over with a new sample C. repeat the hot gravity filtration by pouring the filtrate back through the same funnel D. repeat the hot gravity filtration using a clean funnel a new piece of filter paper