Past exam of the chemistry course of the year 1 of the natural sciences course of the University of Cambridge / 2025 / 4 / b / iv / Solution

At pH $3$, $[{\mathrm{H}}^{+}]=10^{-3}\mathrm{M}$, so the nitrate concentration is $0.001+2(0.1)=0.201\mathrm{M}$. With ideal thermodynamic activities,HenceThe activity of nitric oxide is $0.1$ because the supplied pressure is $0.1\mathrm{bar}$ and the gas standard is $1\mathrm{bar}$. This numerical result additionally approximates zinc and nitrate thermodynamic activities by their standard-concentration ratios; without their activity coefficients, a more precise nonideal value is not specified.