1. Tardigrade
  2. Question
  3. Chemistry
  4. In view of the signs of ΔrG° for the following reactions PbO2 + Pb → 2 PbO, ΔrG° < 0 SnO2 + Sn → 2 SnO, ΔrG° > 0 Which oxidation states are more characteristic for lead and tin?

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Q. In view of the signs of $\Delta_rG°$ for the following reactions
$PbO_2 + Pb \to 2 PbO, \Delta_{r}G^{\circ} < 0$
$SnO_2 + Sn \to 2 SnO, \Delta_{r}G^{\circ} > 0$
Which oxidation states are more characteristic for lead and tin?

Thermodynamics

Solution:

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Since$\Delta G^{\circ} < 0$ i.e., it is negative. Therefore, the reaction is spontaneous in the forward direction. This suggest that $Pb^{2+}$ is more stable than $Pb^{4+}$
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Since $\Delta G^{\circ} > 0$ i.e., it is positive, therefore, the reaction is non-spontaneous in the forward direction. But it will be spontaneous in the backward direction. This suggests that $Sn^{2+}$. These facts are also supported by the inert pair effect down the group.