5.2.2 - Enthalpy and entropy

Question 1

The enthalpy and entropy changes of a reaction both have a negative sign.
Discuss how the feasibility of this reaction will change as the temperature increases. (3)

Answer 1

• Reaction becomes / is less feasible / not feasible as ΔG increases
• TΔS becomes / is more negative than ΔH
• TΔS becomes more negative / TΔS decreases

Question 2

Three processes are given below.
For each process, state and explain whether the change would be accompanied by an increase or
decrease in entropy.
a) The freezing of water.
b) The reaction of calcium carbonate with hydrochloric acid.
c) The formation of O3(g) from O2(g).

Answer 2

a) (entropy) decreases as (solid / ice has) less disorder / more order / fewer ways of arranging energy / less freedom / less random molecules

b) entropy) increases as (CO2) gas is formed

c) entropy decreases as 3 mol O2 form 2 mol O3 / 3O2 → 2O3 / 3 mol gas form 2 mol gas