Question 1

Which of the following best describes entropy ($S$) in a chemical system?

Accepted Answer

Entropy is the measure of disorder, randomness, or chaos in a system.

Question 2

According to the Second Law of Thermodynamics, what happens to the entropy of the universe during a spontaneous process?

Accepted Answer

The entropy of the universe increases.

Question 3

Which of the following factors does NOT directly affect the entropy of a system?

Accepted Answer

Color of the molecules

Question 4

Which of the following substances has the greatest standard molar entropy ($S^\circ$) at 25°C and 1 atm?

Accepted Answer

$\mathrm{CO_2 (g)}$

Question 5

Consider the following reaction at standard conditions:

$\mathrm{2SO_2 (g) + O_2 (g) \rightarrow 2SO_3 (g)}$

What is the sign of $\Delta S$ for this reaction?

Accepted Answer

$\Delta S$ is negative because the number of gas molecules decreases.

Question 6

Which process will result in an increase in entropy ($\Delta S > 0$)?

Accepted Answer

Evaporating liquid ethanol at room temperature

Question 7

A sample of $\mathrm{CH_4 (g)}$ is transferred from a 5 L container to a 1 L container at constant temperature. What happens to the entropy of the system?

Accepted Answer

Entropy decreases because the number of possible arrangements is reduced.

Question 8

Which of the following reactions is most likely to have a positive $\Delta S$?

Accepted Answer

$\mathrm{CaCO_3 (s) \rightarrow CaO (s) + CO_2 (g)}$

Question 9

Which statement is TRUE regarding entropy changes in chemical reactions?

Accepted Answer

Entropy change depends on the number of moles of products and reactants.

Question 10

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

Accepted Answer

Boiling water at 100°C

Question 11

A reaction occurs in which $\mathrm{NaHCO_3 (s)}$ is heated to produce $\mathrm{Na_2CO_3 (s)}$, $\mathrm{CO_2 (g)}$, and $\mathrm{H_2O (g)}$. What is the sign of $\Delta S$ for this reaction?

Accepted Answer

$\Delta S$ is positive because gases are produced.

Question 12

Which of the following statements about entropy is correct?

Accepted Answer

Entropy is a measure of the disorder or randomness in a system.

Question 13

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

Accepted Answer

Condensing water vapor to liquid

Question 14

Which process is most likely to have a negative $\Delta S$?

Accepted Answer

Formation of water from hydrogen and oxygen gases ($\mathrm{2H_2 (g) + O_2 (g) \rightarrow 2H_2O (l)}$)

Question 15

Which of the following best explains why gases generally have higher entropy than solids?

Accepted Answer

Gases have more molecular degrees of freedom and more possible arrangements.

Question 16

A chemical reaction occurs in a closed container at constant temperature: $\mathrm{2NH_3 (g) \rightarrow N_2 (g) + 3H_2 (g)}$. What happens to the entropy of the system?

Accepted Answer

Entropy increases because the number of gas molecules increases.

Question 17

Which of the following statements is FALSE regarding entropy?

Accepted Answer

Entropy always decreases in spontaneous processes.

Question 18

Which of the following processes will result in a decrease in entropy?

Accepted Answer

Condensing steam into liquid water

Question 19

Which of the following is a correct statement about the entropy change ($\Delta S$) when a solid is heated and melts?

Accepted Answer

$\Delta S$ is positive because the number of possible arrangements increases.

Entropy: Concepts, Factors, and Changes in General Chemistry

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