InterviewSolution
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InterviewSolution
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Consider an electrochemical cell: `A(s)|A^(n+)(aq,2M)||B^(2n+)(aq,1M)|B(s)`. The value of `DeltaH^(theta)` for the cell reaction is twice that of `DeltaG^(theta)` at 300K. If the emf of the cell is zero, the `DeltaS^(theta)` (in `KJ^(-1)mol^(-1)`) of the cell reaction per mole of B formed at 300 K is ________ (Given: ln (2)=0.7, R (universal gas constant)=8.3 `JK^(-1)mol^(-1)`. H,S and G are enthalpy, entropy an Gibs energy, respectively). |
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Answer» Correct Answer - A::B `(-11.62)` `underset(DeltaH^(o)=2DeltaG_(O)^(o))(A(s)|A^(+n)(aq,2M))||B^(+2n)underset(E_(cell)=0)((aq,1M)|B(s))` Cell Rx `[AtoA^(+n)+ n e^(-)]xx2` `B^(+2n)+2n e^(-)toB(s)` `2A(s)+underset(1M)(B^(+2n))(aq)tounderset(2M)(2A^(+n))(aq)+B(s)` `DeltaG=DeltaG^(o)+RT" ln "([A^(+n)]^(2))/([B^(+2n)])` `DeltaG^(o)=-RT" ln "([A^(+n)]^(2))/([B^(+2n)])=-RT.ln(2^(2))/(1)=-RT.ln4` `DeltaG^(o)=DeltaH^(o)-TDeltaS^(o)` `DeltaG^(o)=2DeltaG^(o)-TDeltaS^(o)` `DeltaS^(o)=(DeltaG^(o))/(T)=-(RTln4)/(T)=-8.3xx2xx0.7=-11.62J//K.mol` |
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