Question 1

Which of the following correctly ranks the entropy (S°) of a substance in the solid, liquid, and gas phases from lowest to highest?

Accepted Answer

Solid \u003c Liquid \u003c Gas

Question 2

Which of the following best explains why the entropy of a gas is higher than that of a liquid or solid?

Accepted Answer

Gas particles have more freedom of movement and occupy a larger volume.

Question 3

A sample of water is heated from ice at 0°C to steam at 100°C. During which phase change does the entropy increase the most?

Accepted Answer

Boiling (liquid water to steam)

Question 4

Which of the following processes results in a decrease in entropy?

Accepted Answer

Condensation of water vapor to liquid water

Question 5

Which of the following best describes the molecular arrangement in a solid compared to a gas?

Accepted Answer

Molecules in a solid are more ordered and have less freedom of movement than in a gas.

Question 6

A chemical reaction occurs in which two gases combine to form a solid. What happens to the entropy of the system?

Accepted Answer

Entropy decreases because the system becomes more ordered.

Question 7

Which of the following statements about entropy is correct?

Accepted Answer

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

Question 8

Consider the following processes:
I. Freezing of water
II. Evaporation of alcohol
III. Dissolving sugar in tea
Which process(es) involve an increase in entropy?

Accepted Answer

II and III only

Question 9

Which of the following equations correctly represents the change in entropy (ΔS) for a process?

Accepted Answer

ΔS=$$q_{rev}T$$

Question 10

A student places a sealed container of solid iodine in a warm room. Over time, the solid iodine disappears and the container fills with purple vapor. What happens to the entropy of the system?

Accepted Answer

Entropy increases because the solid is converted to a gas.

Question 11

Which of the following real-life scenarios best illustrates an increase in entropy?

Accepted Answer

A clean room becoming messy over time

Question 12

Which of the following changes would result in the greatest increase in entropy for a sample of a pure substance?

Accepted Answer

Vaporizing the liquid to a gas

Question 13

Which of the following best describes the entropy change when sodium chloride dissolves in water?

Accepted Answer

Entropy increases because the ions are dispersed in solution.

Question 14

A reaction occurs in which the number of gas molecules decreases from 4 to 2. What is the expected sign of ΔS for this reaction?

Accepted Answer

Negative, because the system becomes more ordered.

Question 15

Which of the following statements is true regarding the standard molar entropy (S°) of elements at 25°C?

Accepted Answer

Gases have higher standard molar entropy than solids or liquids.

Entropy and States of Matter

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