Page 1 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer.pdf
CHEM 4551
Practice
Problems
Keys
Dr. Angie Spencer
(last edit Fa_25)
1
-2026 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer
,Page 2 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer.pdf
Module 1 Practice Problems
1. A) ΔS is positive since the number of moles of gas molecules is greater on the products side
vs. the reactant side; also greater number of independently moving particles on the
products side vs. the reactant side
B) ΔH is negative (exothermic reaction)
C) ΔG is negative at all temperatures
D) Ea is the activation energy of the reaction-the minimum amount of energy required for
the reaction to occur; as the Ea increases, the rate decreases
2.
3.
(up to 5 hydrogen bonds can form)
2
-2026 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer
, Page 3 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer.pdf
4. Stearic acid is amphiphilic and has a polar head group with a single nonpolar tail. It will
aggregate to form micelles in water. If the carboxylic acid functional group is absent, we
simply have a hydrophobic hydrocarbon, and it will form an unstructured aggregate in
water.
5. a) amphiphilic
b) bilayer
c)
d) The hydrophobic effect describes how this structure forms. The water that forms cages
around the nonpolar tails in the absence of the structural aggregate is low in entropy.
When the molecules aggregate, the hydrophobic tails come together, excluding water, and
the water cages are released into the bulk, increasing the entropy.
6. ionic interactions are stronger in the nonpolar environment inside of a folded protein; this
is explained by the dielectric constant of the ‘solvent’ being low for the protein interior; as
the ε (dielectric constant) decreases, the force of attraction between opposite charges
increases
7.
[2 − 𝑃𝐺] 1
𝐾= = = 0.2
[3 − 𝑃𝐺) 6
𝐽
∆𝐺 °′ = −𝑅𝑇𝑙𝑛𝐾 = −8.314 ∗ 310 𝐾 ∗ ln(0.2) = 4 𝑘𝐽
𝑚𝑜𝑙 𝐾
8. C
3
-2026 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer
CHEM 4551
Practice
Problems
Keys
Dr. Angie Spencer
(last edit Fa_25)
1
-2026 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer
,Page 2 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer.pdf
Module 1 Practice Problems
1. A) ΔS is positive since the number of moles of gas molecules is greater on the products side
vs. the reactant side; also greater number of independently moving particles on the
products side vs. the reactant side
B) ΔH is negative (exothermic reaction)
C) ΔG is negative at all temperatures
D) Ea is the activation energy of the reaction-the minimum amount of energy required for
the reaction to occur; as the Ea increases, the rate decreases
2.
3.
(up to 5 hydrogen bonds can form)
2
-2026 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer
, Page 3 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer.pdf
4. Stearic acid is amphiphilic and has a polar head group with a single nonpolar tail. It will
aggregate to form micelles in water. If the carboxylic acid functional group is absent, we
simply have a hydrophobic hydrocarbon, and it will form an unstructured aggregate in
water.
5. a) amphiphilic
b) bilayer
c)
d) The hydrophobic effect describes how this structure forms. The water that forms cages
around the nonpolar tails in the absence of the structural aggregate is low in entropy.
When the molecules aggregate, the hydrophobic tails come together, excluding water, and
the water cages are released into the bulk, increasing the entropy.
6. ionic interactions are stronger in the nonpolar environment inside of a folded protein; this
is explained by the dielectric constant of the ‘solvent’ being low for the protein interior; as
the ε (dielectric constant) decreases, the force of attraction between opposite charges
increases
7.
[2 − 𝑃𝐺] 1
𝐾= = = 0.2
[3 − 𝑃𝐺) 6
𝐽
∆𝐺 °′ = −𝑅𝑇𝑙𝑛𝐾 = −8.314 ∗ 310 𝐾 ∗ ln(0.2) = 4 𝑘𝐽
𝑚𝑜𝑙 𝐾
8. C
3
-2026 CHEM 4551 Practice Problems KeysAnswer CHEM 4551 Practice Problems KeysAnswer
