$$\Delta S = \frac{q_{\text{rev}}}{T}$$

$$\Delta S_{\text{univ}} \u003e 0$$

$$\Delta S_{\text{surr}} = -\frac{\Delta H_{\text{sys}}}{T}$$

Question 1

Which of the following statements best describes the First Law of Thermodynamics?

Accepted Answer

The total energy of the universe is a constant; energy can be converted from one form to another.

Question 2

Which of the following processes is spontaneous under standard conditions?

Accepted Answer

Ice melting at 10°C.

Question 3

Which equation correctly relates entropy change to heat transfer in a reversible process at constant temperature?

Accepted Answer

$$\Delta S = \frac{q_{	ext{rev}}}{T}$$

Question 4

According to the Second Law of Thermodynamics, which of the following is true for any spontaneous process?

Accepted Answer

$$\Delta S_{	ext{univ}} \u003e 0$$

Question 5

Which of the following changes will increase the entropy of a system?

Accepted Answer

Increasing the number of independently moving molecules.

Question 6

Which of the following best describes a reversible process?

Accepted Answer

A process that can be reversed by exactly retracing its steps, maximizing work done by the system.

Question 7

The entropy of a pure crystalline substance at absolute zero is:

Accepted Answer

$$S = k \ln W$$, where $$W = 1$$

Question 8

Which of the following reactions would result in an increase in entropy?

Accepted Answer

Dissolving NaCl(s) in water.

Question 9

Given the reaction: $$2NO(g) + O_2$(g) \rightarrow 2NO_2(g)$$, predict the sign of $$\Delta S.$$

Accepted Answer

$$\Delta S \u003c 0$$

Question 10

Which of the following is the correct expression for the entropy change of the surroundings for a process at constant pressure?

Accepted Answer

$$\Delta S_{	ext{surr}} = -\frac{\Delta H_{	ext{sys}}}{T}$$

Question 11

Which of the following statements about Gibbs free energy is correct?

Accepted Answer

A reaction is at equilibrium if $$\Delta G = 0.$$

Question 12

Which of the following equations correctly relates the standard free energy change to the equilibrium constant $$K$$?

Accepted Answer

$$\Delta G^\circ = -RT \ln K$$

Question 13

Which of the following best explains why ATP hydrolysis is used to drive nonspontaneous reactions in cells?

Accepted Answer

ATP hydrolysis releases free energy that can be coupled to nonspontaneous processes.

Question 14

Which of the following factors does NOT increase the standard molar entropy of a substance?

Accepted Answer

Decreasing the temperature.

Question 15

For the reaction $$H_2O(l) \rightarrow H_2O(s)$$, which of the following is true about $$\Delta H$$, $$\Delta S$$, and spontaneity?

Accepted Answer

$$\Delta H \u003c 0$$, $$\Delta S \u003c 0$$, spontaneous at low temperatures.

Question 16

Which of the following is a correct statement about microstates and entropy?

Accepted Answer

Entropy increases as the number of microstates increases.

Question 17

Which of the following is the correct formula for calculating the entropy change for a reaction using standard molar entropies?

Accepted Answer

$$\Delta S^\circ = \sum n S^\circ_{	ext{products}} - \sum m S^\circ_{	ext{reactants}}$$

Question 18

A chemical reaction has $$\Delta H \u003e 0$$ and $$\Delta S \u003e 0. $$Under what conditions will the reaction be spontaneous?

Accepted Answer

At high temperatures.

Question 19

Which of the following best describes the relationship between free energy and equilibrium?

Accepted Answer

At equilibrium, $$\Delta G = 0$$ and $$Q = K.$$

Chapter 19: Chemical Thermodynamics – Study Notes

Study Guide - Practice Questions