A sample of organic material weighing 1.058 g is decomposed by the Kjeldahl method. The ammonia is distilled into 50.0 mL of0.100 M $\mathrm{HCl}$ solution. The excess remaining acid required 10.10 mL of0.098 M $\mathrm{NaOH}$ solution. The percentage of nitrogen in the sample would be

Amount of $\mathrm{HCl}$ to start with  $=\left(50.0\times {10}^{-3}\mathrm{L}\right)\left(0.10\mathrm{molL}=50.0\times {10}^{-4}\mathrm{mol}\right.$

Amount of excess $\mathrm{HCl}$ $\mathrm{HCl}=\left(10.0\times {10}^{-3}\mathrm{L}\right)\left(0.098\mathrm{molL}=9.8\times {10}^{-4}\mathrm{mol}\right.$

Amount of ${\mathrm{NH}}_3$ evolved or amount of N in the compound  $=(50.0-9.8)\times {10}^{-4}\mathrm{mol}=41.2\times {10}^{-4}\mathrm{mol}$

Mass of N in the compound $=\left(41.2\times {10}^{-4}\mathrm{mol}\right)\left(14\mathrm{g}{\mathrm{mol}}^{-1}\right)=0.05768\mathrm{g}$

Percentage of N in the compound $=\frac{0.05768}{1.058}\times 100=5.45\mathrm{\%}$