Answer to Question #346582 in General Chemistry for Mayo

Question

PROBLEM:

Choose the member with the higher entropy in each of the following pairs, and justify your choice [assume constant temperature, except in part (e)]:

(a) 1 mol of SO₂(g) or 1 mol of SO3(g)

(b) 1 mol of CO₂(s) or 1 mol of CO₂(g)

(c) 3 mol of O₂(g) or 2 mol of O3(g)

(d) 1 mol of KBr(s) or 1 mol of KBr(aq)

(e) seawater at 2°C or at 23°C

(f) 1 mol of CF4(g) or 1 mol of CCl4(g)

Answer 1

a)

SO_2(g)  < SO_3(g)

Because, In an exothermic reaction, the external entropy (entropy of the surroundings) increases. In an endothermic reaction, the external entropy (entropy of the surroundings) decreases.

The oxidation of SO₂ by O₂ to SO₃ is an exothermic reaction.

b)

CO_2(s)  < CO_2(g)

because the entropy increases as the substance changes from a solid to a liquid

c)

3O_2(g)  > 2O_3(g)

Because, In an exothermic reaction, the external entropy (entropy of the surroundings) increases. In an endothermic reaction, the external entropy (entropy of the surroundings) decreases. The entropy decreases because the above reaction is endothermic.

d)

KBr_(s)  < KBr_(aq)

because the entropy increases as the substance changes from a solid to a liquid

e)

seawater 2°C < 23°C

because the entropy increases as the temperature increases

f)

CF_4(g)  > CCl_4(g)

Because, In an exothermic reaction, the external entropy (entropy of the surroundings) increases. In an endothermic reaction, the external entropy (entropy of the surroundings) decreases. The entropy decreases because the above reaction is endothermic.