CAIE A Level Chemistry Chap # 23, Entropy and Gibbs Free Energy

What is entropy?

• The measure of randomness or disorder in a system

• The measure of energy dispersal in a system

• The measure of temperature change in a system

• The measure of pressure change in a system

Which of the following is a spontaneous change? (Select all that apply)

• Sugar dissolving in water

• Water turning to ice at 10°C

• Ethanol vaporizing at 20°C

• Limestone decomposing at room temperature

What happens to the entropy when a solid melts?

• Entropy increases

• Entropy decreases

• Entropy remains the same

• Entropy cannot be determined

Which substance has the highest entropy?

• Diamond

• Graphite

• Calcium

• Lead

What is the standard molar entropy of water?

• 48.0 J/K mol

• 69.9 J/K mol

• 188.7 J/K mol

• 213.6 J/K mol

Which type of substances have low entropy?

• Gases

• Solids

• Liquids

• Aqueous solutions

In the reaction 2N₂O₅(g) → 4NO₂(g) + O₂(g), what is the entropy change of the system?

• Positive

• Negative

• Zero

• Cannot be determined

What is the entropy change of the system for the reaction 2Ca(s) + O₂(g) → 2CaO(s)?

• Increases

• Decreases

• Remains Same

• Information missing for correct evaluation

Which of the following reactions has a positive total entropy change?

• S(s) + H₂(g) → H₂S(g)

• 2C(graphite) + N₂(g) → C₂N₂(g)

• 4P(s) + 5O₂(g) → P₄O₁₀(s)

• C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(l)

How does increasing the temperature affect the ability of zinc carbonate to undergo thermal decomposition?

• Increases the entropy change of the system

• Decreases the entropy change of the system

• Has no effect on the entropy change of the system

• Cannot be determined