The Foundations of Chemistry

*55.(a) Name three biopolymers found in animals. (b) Name

at least one biopolymer that is composed of identical

monomers.

*56.Name the three types of monomers that are found in DNA.

Give a structural formula of an example of each.

CONCEPTUAL EXERCISES

*57.Nylon is decomposed by acids, but polyethylene is not.

Suggest an explanation for this difference in behavior.

*58.How does the heat of combustion of ethyl alcohol com-

pare with the heats of combustion of low-molecular-weight

saturated hydrocarbons on a per-mole basis and on a per-

gram basis?

BUILDING YOUR KNOWLEDGE

*59.A laboratory procedure calls for oxidizing 2-propanol to

acetone using an acidicsolution of K 2 Cr 2 O 7. An insuffi-

cient amount of K 2 Cr 2 O 7 is on hand, however, so the

laboratory instructor decides to use an acidic solution of

KMnO 4 instead. What mass of KMnO 4 is required to carry

out the same amount of oxidation as 1.00 g of K 2 Cr 2 O 7?

*60.The chemical equation for the water gas reaction is

C(s)H 2 O(g) 34 CO(g)H 2 (g)

At 1000 K, the value of Kpfor this reaction is 3.2. When

we treat carbon with steam and allow the reaction to reach

equilibrium, the partial pressure of water vapor is observed

to be 15.6 atm. What are the partial pressures of CO and

H 2 under these conditions?

*61.(a) In aqueous solution, acetic acid exists mainly in the

molecular form (Ka1.8 10 ^5 ). Calculate the freezing

point depression for a 0.10 molal aqueous solution

of acetic acid, ignoring any ionization of the acid.

Kf1.86°C/molal for water. (b) In nonpolar solvents such

as benzene, acetic acid exists mainly as dimers

as a result of hydrogen bonding. Calculate the freezing

point depression for a 0.10 molal solution of acetic acid in

benzene. Kf5.12°C/molal for benzene. Assume com-

plete dimer formation.

*62.What is the pH of a 0.10 Msolution of sodium benzoate?

Ka6.3 10 ^5 for benzoic acid, C 6 H 5 COOH. Would

this solution be more or less acidic than a 0.10 Msolution

of sodium acetate? Ka1.8 10 ^5 for acetic acid,

CH 3 COOH.

CH 3 CCCH 3

OO

OOH

H

*47.Write the structural formula of the carbohydrate found in

deoxyribonucleic acid (DNA). How does this carbohydrate

differ from the one found in ribonucleic acid (RNA)?

*48.Write structural formulas of the four bases found in DNA.

Circle at least one functional group on each that gives the

compound its base properties.

*49.Draw a short segment of the DNA biopolymer that contains

three each of the phosphate, carbohydrate, and base groups.

*50.In the double-strand form of DNA the base groups are

paired. What base is found paired (hydrogen bonded) with

thymine?

Mixed Exercises

*51.Identify the major products of each reaction.

*52.Identify the major products of each reaction.

*53.Write a structural formula for each of the following

compounds:

(a) CH 3 OH (d) CH 3 OCH 3

(b) CH 3 COOH (e) CH 3 CHCHCH 2 CH 3

(c) CH 3 CHOHCH 3

*54.Write a structural formula for each of the following

compounds:

(a) CH 3 ONO 2 (d) ClCH 2 CHCHCl

(b) CH 3 CHCH 2 (e) CH 3 CH 2 CH 2 ONa

(c) CH 3 CH 2 CH 2 OH

O

C OH

OCCH 3

O

(c)

NaOH(aq)

heat

(b)

O

CH 3 CH 2 COCH 3

KOH(aq)

heat

(a) CH 2 OHNa

(c)

O

CH 3 CH

MnO 4 

H

(b)

O

C OHCH 3 OH

H 2 SO 4

heat

CH 3

2NaOH

O

C OH

OH

(a) 

1140 CHAPTER 28: Organic Chemistry II: Shapes, Selected Reactions, and Biopolymers