Question

Which of the following would you predict to have a positive value for º ?

AgCl(s) → Ag+(aq) + Cl-(aq)


H2O(g) → H2O(l)


2 Na(s) + Cl2(g) → 2NaCl(s)


Br2(l) → Br2(s)

Answer 1

Given:

AgCl (s) ===> Ag+ (aq) + Cl- (aq)
- negative entropy

H2O(g) ===> H2O(l)
- positive entropy

2Na (s) + Cl2 (g) ===> 2NaCl (s)
- positive entropy

Br2(l) ===> Br2 (s)
-positive entropy

They are identified to have positive or negative values of entropy based on the phases of the reactants and products.