Consider an electrochemical cell- A s - A n - aq - 2 M B 2 n - aq - 1 M - B s - The value of - H - for the cell reaction is twice that of - G - at 300 K- Ifth emf of the cell is zero- the - S - in -JK -1 mol -1 of the cell reaction per mole of B formed at 300 K is J mol -1 K -1 Given- ln 2-0-7- R universal gas constant 8-3 JK -1 mol -1 - H - S and G are enthalpy- entropy and Gibbs energy- respectively-

A(s)|A^n+ (aq, 2 M)|| B^2n+ (aq, 1 M)|B(s) 2A(s) → 2A^n+ + 2ne^ B^2n+ + 2ne^ → B(s) 2A(s) + B^2n+→ 2A^n+ + B(s) Q = [A^n+]^2/B^2n+ = 2 × 2/1 = 4 Δ G^∘ = Δ H^∘ ...

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Standard XII

Chemistry

Gibb's Energy and Nernst Equation

Consider an e...

Question

Consider an electrochemical cell: $A (s) | A^{n +} (a q, 2 M) | | B^{2 n +}$ (aq, 1 M)|B(s). The value of $Δ H^{\circ}$ for the cell reaction is twice that of $Δ G^{\circ}$ at 300 K. If th emf of the cell is zero, the $Δ S^{\circ} (i n J K^{- 1} m o l^{- 1})$ of the cell reaction per mole of B formed at 300 K is $J m o l^{- 1} K^{- 1}$
(Given: ln(2) =0.7, R (universal gas constant) 8.3 $J K^{- 1} m o l^{- 1}$ . H, S and G are enthalpy, entropy and Gibbs energy, respectively.)

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Solution

$A (s) | A^{n +} (a q, 2 M) | | B^{2 n +} (a q, 1 M) | B (s)$
$2 A (s) \to 2 A^{n +} + 2 n e^{-}$
$B^{2 n +} + 2 n e^{-} \to B (s)$
$2 A (s) + B^{2 n +} \to 2 A^{n +} + B (s)$
$Q = \frac{[A^{n +}]^{2}}{B^{2 n +}} = \frac{2 \times 2}{1} = 4$
$Δ G^{\circ} = Δ H^{\circ} - T Δ S^{\circ}$
$Δ H^{\circ} = 2 Δ G^{\circ}$
$E_{c e l l}^{0} = \frac{R T}{2 n F} l n 4$
$Δ G^{\circ} = - 2 n \times F \times \frac{R T}{2 n F} l n 4$
$Δ G^{\circ} = - R T l n 4$
$Δ S^{\circ} = \frac{Δ H^{0} - Δ G^{0}}{T} = \frac{Δ G^{\circ}}{T} = - \frac{R T l n 4}{T}$
$Δ S^{\circ} = - 8.314 \times 1.4$
$= - 11.62 J m o l^{- 1} K^{- 1}$

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Q. Consider an electrochemical cell:

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(aq, 1 M)|B(s). The value of

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Δ S^{\circ} (i n J K^{- 1} m o l^{- 1})

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