Question #44208

Consider the following electrochemical cell at 298 K:

$\ce{Pt(s) | H2(g, 1 bar) | HA(aq, C) || Cu^{2+}(aq, 1 M) | Cu(s)}$

where $\ce{HA}$ is a weak monoprotic acid with a dissociation constant $K_a = 1.0 \times 10^{-5}$. When the concentration of $\ce{HA}$ is $C_1 = 0.1 \text{ M}$, the measured cell potential is $E_1$. When the $\ce{HA}$ solution in the anodic compartment is diluted to a concentration $C_2 = 7.5 \times 10^{-6} \text{ M}$, the cell potential becomes $E_2$. Calculate the magnitude of the change in cell potential, $|E_2 - E_1|$ in mV.

(Given: $\frac{2.303 RT}{F} = 0.06 \text{ V}$, $\log 2 = 0.30$, $\log 3 = 0.48$. Assume activity coefficients are unity.)