Question

Entropy (S) The second factor involved in determining whether or not a process is spontaneous is the change in randomness or entropy (AS). Entropy is represented by the symbol S. Again, experience can help us understand the relationship between entropy and spontaneous processes. If we look at the two drawings below, we can predict which picture represents the stack of marbles "before" and after they are bumped. We expect the stack of marbles (less random, lower entropy) to be the initial state and the scattered marbles (more random; greater entropy) to be the final state. An increase in entropy (randomness) is spontaneous and a decrease in entropy (randomness) is non-spontaneous. More Entropy (S) or More Random Less Entropy (S) or Less Random Critical Thinking Questions - Entropy 5. Identify whether entropy increases or decreases for each of the following changes. Explain a) evaporation of a liquid b) freezing of a liquid c) precipitation of a solid from ions in solution d) CaCO3(e) → CaO x + CO2 (give 2 reasons) e) N2(g) + 3H2(g) + 2NH3(g) 10-3

Answer 1

Critical Thinking Questions - Entropy 5. Identify whether entropy increases or decreases for each of the following changes. Explain a) evaporation of a liquid Entropy increases b) freezing of a liquid Entropy decreases c) precipitation of a solid from ions in solution Entropy decreases d) CaCO3(s) Cai) + CO2 (give 2 reasons) Entropy increases e) Na(a) + 3H2(g) + 2NH3(g) Entropy decreases

5.a) For evaporation of liquid , the liquid particles transfered into high disorderness gaseous particle and consequently, entropy increases.

5.b) For freezing of liquid, the liquid particles transfered into less disorderness solid particles and consequently, entropy decreases.

5.c) For precipitation of solid from ions in solution is simmilar like freezing of liquid where the ion particles in solutions are transfered into less disorderness solid particles and consequently, entropy decreases.

5.d) For this reaction, entropy increases for two different reasons

(i) From one CaCO3 molecule 2 product molecules are formed.

(ii) The product CO2 is gaseous in nature; which created high disorderness.

5.e) For this reaction, entropy decreases as from 4 gaseous reactant molecule 2 gaseous product molecule formed. Therefore, disorderness decreases and consequently, entropy decreases.