Question

$Pb{O}_2\to PbO\Delta G_{298}<0$
$Sn{O}_2\to SnO\Delta G_{298}>0$
Most probable oxidation state of Pb & Sn will be :

• A. $P{b}^{+4},S{n}^{+2}$
• B. $P{b}^{+4},S{n}^{+2}$
• C. $P{b}^{+2},S{n}^{+2}$
• D. $P{b}^{+2},S{n}^{+4}$

Answer 1

Answer: (D)

$Pb{O}_2\to PbO$
$\Delta G_{298}<0$
For this reaction $\Delta G$ is negative, hence $P{b}^{2+}$ is more stable than $P{b}^{4+}$.
$Sn{O}_2\to SnO\Delta G_{298}>0$
For this reaction $\Delta G$ is positive,
hence $S{n}^{4+}$ is more stable than $S{n}^{2+}$.
because for spontaneous change $\Delta G$ must be negative.