It is noticed that Pb2+ is more stable than Pb4+ but Sn2+ is less stable than Sn4+. Observe the following reactions. PbO2 + Pb 2PbO; rG (1) SnO2 + Sn 2SnO; rG (2) Identify the correct set from the following
- rG (1) > 0; rG (2) < 0
- rG (1) < 0; rG (2) > 0
- rG (1) < 0; rG (2) < 0
- rG (1) > 0; rG (2) > 0
Answer
(2) rG (1) < 0; rG (2) > 0
Solution
Both reactions convert the +4 and 0 states into the +2 state.
Reaction 1: Pb2+ is more stable than Pb4+ (inert pair effect) formation of PbO is favourable rG (1) < 0.
Reaction 2: Sn4+ is more stable than Sn2+ formation of SnO from SnO2 and Sn is not favourable rG (2) > 0.
Answer: (2)