Solution
= Solution
Pure solid CeO$_2$ and liquid water have unit <thermodynamic activity> in the stated approximation, so
$$
Q=\frac{a_{\rm Ce^{3+}}^4a_{\rm CH_3COO^-}}
{a_{\rm C_2H_5OH}a_{\rm H^+}^{11}},
\qquad
\boxed{E=E^\circ-\frac{RT}{4F}\ln Q}.
$$
The power 11 and the four-electron denominator follow from the balanced conventional reaction; using the deposition reaction without reversing the potential would give inconsistent signs.