Question 1

Which of the following best describes a spontaneous process in thermodynamics?

Accepted Answer

A process that occurs without ongoing outside intervention.

Question 2

The first law of thermodynamics states that:

Accepted Answer

Energy cannot be created or destroyed, only converted from one form to another.

Question 3

Which of the following processes results in a decrease in entropy ($$\Delta S \u003c 0) $$for water?

Accepted Answer

Condensation of water vapor on the sides of a cold glass.

Question 4

Which equation correctly expresses the relationship between entropy ($$S$$), the Boltzmann constant ($$K$$), and the number of microstates ($$W$$)?

Accepted Answer

$$S = K \ln W$$

Question 5

Consider the following reaction: $$2N_2O(g) \rightarrow 2N_2(g) + O_2$(g). $$What is the sign of $$\Delta S$$ for this reaction and why?

Accepted Answer

$$\Delta S is $$positive because the number of moles of gas increases.

Question 6

Which of the following statements about the relationship between spontaneity and reaction rate is correct?

Accepted Answer

Spontaneity does not determine the speed of a reaction.

Question 7

According to the second law of thermodynamics, which of the following must be true for a process to be spontaneous?

Accepted Answer

$$\Delta S_{universe} \u003e 0$$

Question 8

Which of the following phase changes for a substance will always result in an increase in entropy ($$\Delta S \u003e 0$$)?

Accepted Answer

Sublimation of a solid to a gas.

Question 9

A diamond ring is stored for many years. Over time, the conversion of diamond to graphite is:

Accepted Answer

Spontaneous but extremely slow.

Question 10

Which of the following best explains why ice melts spontaneously at temperatures above $$0^\circC$$, even though the process is endothermic?

Accepted Answer

The increase in entropy ($$\Delta S \u003e 0) $$compensates for the positive enthalpy change.

Question 11

Which of the following processes will result in the greatest increase in entropy?

Accepted Answer

Subliming dry ice (solid $$CO_2) to$$ $$CO_2$$ gas.

Question 12

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

Accepted Answer

A microstate is the number of energetically equivalent ways to arrange a system.

Question 13

Which of the following chemical reactions would you expect to have a positive entropy change ($$\Delta S \u003e 0$$)?

Accepted Answer

$$CO_2(s$$) \rightarrow $$CO_2(g$$)$$

Question 14

Which of the following scenarios best illustrates the concept of increasing entropy in a real-world context?

Accepted Answer

A drop of ink disperses in a glass of water.

Question 15

If the number of energetically equivalent ways to arrange a system ($$W) $$increases, what happens to the entropy ($$S) of $$the system?

Accepted Answer

Entropy increases.

Question 16

Which of the following processes is most likely to be exothermic and spontaneous under standard conditions?

Accepted Answer

Combustion of gasoline in air.

Question 17

Which of the following best describes the entropy change when salt ($$NaCl) $$dissolves in water?

Accepted Answer

Entropy increases because the arrangement of molecules and ions becomes more disordered.

Question 18

A chemical reaction occurs in which the number of moles of gas decreases. What is the most likely sign of $$\Delta S$$ for this reaction?

Accepted Answer

$$\Delta S is $$negative.

Question 19

Which of the following is NOT a correct prediction for the sign of $$\Delta S$$?

Accepted Answer

Gas $$\rightarrow$$ Solid: $$\Delta S \u003e 0$$

Question 20

Which of the following best explains why the expansion of an ideal gas into a vacuum is a spontaneous process?

Accepted Answer

The process increases the number of microstates, leading to higher entropy.

Ch. 19: Free Energy and Thermodynamics – Study Notes

Study Guide - Practice Questions