Question

Calculate the percentage of nitrogen in ${\mathrm{NH}}_3$ (Atomic Mass Of N =14 An H=1 Amu).

Answer 1

Step 1:- Molecular mass of ${\mathrm{NH}}_3$

Given the atomic mass of N is 14 amu and that of H is 1 amu

Thus the molecular mass of ${\mathrm{NH}}_3$ = $14amu+\left(3\times 1\right)amu=17amu$

Step 2:- Percentage composition of N

Percentage composition of N

= $\frac{\mathrm{atomic}\mathrm{mass}\mathrm{of}\mathrm{N}\times \mathrm{total}\mathrm{numer}\mathrm{of}\mathrm{N}\mathrm{present}\mathrm{in}\mathrm{the}\mathrm{molecule}\times 100\%}{\mathrm{total}\mathrm{molecular}\mathrm{mass}\mathrm{of}{\mathrm{NH}}_3}$

= $\frac{14\mathrm{amu}\times 100\%}{17\mathrm{amu}}$

= $82.35\%$

Thus the percentage composition of N in ${\mathrm{NH}}_3$ is $82.35\%$