For the reaction $PbO_2 \rightarrow PbO$, $\Delta G_{298}

Question

For the reaction $PbO_2 \rightarrow PbO$, $\Delta G_{298} < 0$, and for the reaction $SnO_2 \rightarrow SnO$, $\Delta G_{298} > 0$. The most probable oxidation states of Pb and Sn will be respectively:

Accepted Answer

The given $\Delta G$ values indicate the spontaneity of the decomposition reactions. 
1. **Lead (Pb):** The reaction $PbO_2 (+4) \rightarrow PbO (+2)$ has $\Delta G < 0$, meaning it is spontaneous. This indicates that the **+2 oxidation state** is thermodynamically more stable than the +4 state for Lead. This is due to the **inert pair effect**, where the $6s^2$ electrons are reluctant to participate in bonding.
2. **Tin (Sn):** The reaction $SnO_2 (+4) \rightarrow SnO (+2)$ has $\Delta G > 0$, meaning it is non-spontaneous. This indicates that the **+4 oxidation state** is more stable than the +2 state for Tin.

Thus, the most characteristic states are Pb(+2) and Sn(+4).

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