JAMB - Chemistry (1992 - No. 24)
In which of the following is the entropy change positive?
H2O(I) → H2O(g)
Cu2+(aq) + Fe(s) → Fe2+(aq) + Cu(s)
N2(g) + 3H2(g) → 2NH3(g)
2HCI(g) → H2(g) + CI2(g)
설명
Entropy is the measure of the degree of disorderliness or randomness in a system. It will, however, decrease from gaseous to liquid and to solid states and vice versa.
This implies for option A, as you move from reactants(liquid H\(_2\)O) to products(gaseous H\(_2\)O), entropy increases because the level of disorderliness increases. (Just liken it to liquid water that needs to be boiled). Hence ΔS = + ve.