Question

Which of the following would have a positive change in standard entropy at constant temperature? Choose all that apply.

CaCO₃ (s)   CaO (s) + O₂(g)
Hg(l) Hg(s)
Ag(CN)₂^- (aq) Ag⁺ (aq) + 2 CN^- (aq)
C₂H₂ (g) + F₂ (g) C₂H₂F₂ (g)
CO₂(g) CO₂(s)

Answer 1

entropy of gas > entropy of aqueous > entropy of liquid > entropy of solid

This is because gas are more free to move around and hence there randomness is more.

Aqueous compound is mixture of solute and solvent and hence randomness is greater than solid form liquid.

In liquid molecules move more freely than solid. So, entropy of liquid is more than solid.

1)

There are gases only on product side.

So, there is more entropy on product side than on reactant side.

So, there is increase in entropy

2)

Liquid is changing too solid.

So, entropy is decreasing

3)

There are more aqueous particle in product than reactant.

So, entropy is increasing

4)

There are more gas in reactant than in product.

So, there is more entropy on reactant side than on product side.

So, there is decrease in entropy

5)

There are gases only on reactant side.

So, there is more entropy on reactant side than on product side.

So, there is decrease in entropy

Answer: option 1, 3