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(B) The cell reaction is: $QH_2 + 2Ag^+ ightarrow Q + 2Ag + 2H^+$. $E^o_{	ext{cell}} = E^o_{Ag^+/Ag} - E^o_{Q/QH_2} = 0.8 - 0.7 = 0.1 \ V$. Using t

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$6$

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(B) The cell reaction is: $QH_2 + 2Ag^+ ightarrow Q + 2Ag + 2H^+$. $E^o_{	ext{cell}} = E^o_{Ag^+/Ag} - E^o_{Q/QH_2} = 0.8 - 0.7 = 0.1 \ V$. Using the Nernst equation: $E_{	ext{cell}} = E^o_{	ext{cell}} - \frac{0.06}{2} \log \frac{[H^+]^2}{[Ag^+]^2}$. Given $E_{	ext{cell}} = 0.4 \ V$,$[Ag^+] = 1 \ M$: $0.4 = 0.1 - 0.03 \log [H^+]^2 = 0.1 - 0.06 \log [H^+]$. $0.3 = -0.06 \log [H^+]$ $\Rightarrow \log [H^+] = -5$ $\Rightarrow pH = 5$. For a salt of a weak base and strong acid $(NH_4X)$,$pH = 7 - \frac{1}{2} pK_b - \frac{1}{2} \log C$. $5 = 7 - \frac{1}{2} pK_b - \frac{1}{2} \log (0.01)$. $5 = 7 - \frac{1}{2} pK_b - \frac{1}{2} (-2) = 7 - \frac{1}{2} pK_b + 1 = 8 - \frac{1}{2} pK_b$. $\frac{1}{2} pK_b = 3 \Rightarrow pK_b = 6$.

Similar Questions

Which one of the following statements is correct?

Efficiency of the following cell is $84\%$. $A_{(s)} + B^{2+}(aq.) \rightleftharpoons A^{2+}(aq.) + B_{(s)}$; $\Delta H^o = -285 \ kJ$. Then the standard $EMF$ of the cell will be ........... $V$.

Pick out the incorrect statement $:-$

Calculate the $K_C$ and $\Delta G^o$ for the chemical reaction :
$Ni_{(s)} + 2Ag_{(aq)}^{+} \to Ni_{(aq)}^{2+} + 2Ag_{(s)}$ $ [E^o = 1.05 \, V] $

Which of the following statements is not correct?

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