Question

$ { PbO_2 -> PbO \, \Delta G_{298} < 0 }$ $ { SnO_2 -> SnO \, \Delta G_{298} > 0}$ Most probable oxidation state of Pb & Sn will be :

• A. $\ce{ Pb^{+4} , Sn^{+2} } $
• B. $\ce{Pb^{+4} , Sn^{+2} } $
• C. $\ce{ Pb^{+2} , Sn^{+2} } $
• D. $\ce{ Pb^{+2} , Sn^{+4} } $

Answer 1

The Correct Option is D

$ {PbO_2 \to PbO}$ $ {\Delta G_{298} < 0}$ For this reaction $ {\Delta G}$ is negative, hence $ {Pb^{2+}}$ is more stable than $ {Pb^{4+}}$. $ {SnO_2 \to SnO \Delta G_{298} >0}$ For this reaction $ {\Delta G}$ is positive, hence $ {Sn^{4+}}$ is more stable than $ {Sn^{2+}}$. because for spontaneous change $ {\Delta G}$ must be negative.