Question

Which of the following reactions results in an increase in entropy?

A) Reaction 1: NaCl(s) → Na+(aq) + Cl−
B) Reaction 2: CaCO₃(s) → CaO(s) + CO₂(g)
C) Both Reaction 1 and Reaction 2
D) Neither Reaction 1 nor Reaction 2

Answer 1

The reaction 2: CaCO₃(s) → CaO(s) + CO₂(g) results in an increase in entropy because a gas is being produced and the number of molecules is increasing. On the other hand, reaction 1: NaCl(s) → Na+(aq) + Cl− does not result in an increase in entropy, as a solid is dissociating into separate ions in aqueous solution.

Step-by-step explanation:

Entropy generally increases in reactions in which the total number of product molecules is greater than the total number of reactant molecules. Additionally, entropy increases when a substance is broken up into multiple parts or when solid or liquid reactants form gaseous products. Based on these principles, we can determine that Reaction 2: CaCO₃(s) → CaO(s) + CO₂(g) results in an increase in entropy because a gas is being produced and the number of molecules is increasing. On the other hand, Reaction 1: NaCl(s) → Na+(aq) + Cl− does not result in an increase in entropy, as a solid is dissociating into separate ions in aqueous solution.