= Solution
The <Nernst equation> for the six-electron cell reaction is
$$
\boxed{E=E^\circ-\frac{RT}{6F}\ln Q,\qquad
Q=\frac{a_{\mathrm{Zn^{2+}}}^3a_{\mathrm{NO}}^2}{a_{\mathrm{NO_3^-}}^2a_{\mathrm{H^+}}^8}.}
$$
Here pure solid <zinc> and liquid <water> have unit <thermodynamic activity>. For ideal nitric oxide gas, $a_{\mathrm{NO}}=p_{\mathrm{NO}}/p^\circ$ with $p^\circ=1\,\mathrm{bar}$; for ideal dissolved species, $a_i=[i]/c^\circ$. The <reaction quotient> is dimensionless. The <platinum> supplies an electronically conducting surface and is absent from the net <chemical equation>.
Back to article page
