The nitrobenzene in 300 mg of an organic mixture was reduced to phenylhydroxylamine at a constant potential of 20.96 V (versus SCE) applied to a mercury cathode:
C6H5NO2 + 4H+ + 4e¯ ( C6H5NHOH + H2O
The sample was dissolved in 100 mL of methanol. After electrolysis for 30 min, the reaction was judged complete. An electronic coulometer in series with the cell indicated that the reduction required 33.47 C. Calculate the percentage of C6H5NO2 in the sample.