Chemistry - Electrochemistry Question with Solution | TestHub

Given cell:

$Co(s)|C{o}^{2+}(M_1)||H^{+}(M_2)|H_2(g,p_1)|Pt$

Cell reaction:

$Co+2H^{+}\to C{o}^{2+}+H_2$

$$E=E^{\circ }-\frac{0.0591}{2}\log \frac{[C{o}^{2+}]P_{H_2}}{[H^{+}{]}^2}$$

(A) Volume change does not change concentration, so the electromotive force (emf) is unchanged.

(B) Increasing the molarity of $H^{+}$ from $0.1M$ to $0.5M$ decreases $Q$, hence the emf increases.

(C) Decreasing $H_2$ pressure decreases $Q$, so the emf increases.

(D) The mass of solid cobalt does not appear in the Nernst equation, so there is no effect.

(B) and (C)