Question

Calculate the percentage of nitrogen in ammonium nitrate $\left({\mathrm{NH}}_4{\mathrm{NO}}_3\right)$.

Answer 1

Step 1: Atomic mass

• $\mathrm{H}=1\mathrm{g}/\mathrm{mol},\mathrm{N}=14\mathrm{g}/\mathrm{mol},\mathrm{O}=16\mathrm{g}/\mathrm{mol}$

Step 2: Write the formula to find the molecular mass

• The molecular mass of ${\mathrm{NH}}_4{\mathrm{NO}}_3$
• so it is = 1 atom of nitrogen + 4 atoms of hydrogen + 1 atom of nitrogen +3 atoms of oxygen

$$\begin{gathered} =(2\mathrm{x}14)+(4\mathrm{x}1)+(3\mathrm{x}16) \\ =80\mathrm{g}/\mathrm{mol} \end{gathered}$$

Step 3: Write the formula to find the percentage

• Percentage of Nitrogen in ${\mathrm{NH}}_4{\mathrm{NO}}_3$= $\frac{\mathrm{Mass}\mathrm{of}\mathrm{Nitrogen}}{\mathrm{Mass}\mathrm{of}\mathrm{Nitrogen}\mathrm{in}{\mathrm{NH}}_4{\mathrm{NO}}_3}x100$
• Mass of $\mathrm{two}\mathrm{mole}\mathrm{N}\mathrm{atoms}=2\mathrm{x}14\mathrm{g}/\mathrm{mol}=28\mathrm{g}/\mathrm{mol}$
• Plug in the values,
• Percentage of Nitrogen in ${\mathrm{NH}}_4{\mathrm{NO}}_3$$=\frac{28\mathrm{g}/\mathrm{mol}}{80\mathrm{g}/\mathrm{mol}}x100\%$
• Percentage of Nitrogen in ${\mathrm{NH}}_4{\mathrm{NO}}_3$$=35\%$

Step 4: Write the final answer

Hence, the percentage of nitrogen, $\mathrm{N}$ in ammonium nitrate $\left({\mathrm{NH}}_4{\mathrm{NO}}_3\right)$ is $35\%$