In the decomposition of CaCO3 a gas is produced: CaCO3 (s) → CaO (s) + CO2 (g). Predict the change in entropy for this reaction.

The predicted change in entropy would be:
a. ΔS < 0
b. ΔS = 0
c. ΔS > 0
d. Enthalpy required

My answer is c but could someone check this. Thanks

1 answer

That is correct. Reactions occur spontaneously if dS is +. Gases have more entropy than solids; therefore, this reaction will have a + dS.