Question

The percentage by weight of nitrogen in ammonium nitrate is ______.

Answer 1

Percent by weight:

• It is also referred to as mass percent composition and is expressed as W/W% meaning weight by weight.
• It is defined as the ratio of mass of a solute and the mass of the solution multiplied by $100$.

Step 1: Given data

• The total molecular weight of ammonium nitrate (${\mathrm{NH}}_4{\mathrm{NO}}_3$) is $80$ g/mol with nitrogen, hydrogen and oxygen contributing $28$, $4$ and $48$ g/mol respectively.

Step 2: Use formula

• Use percent by weight formula i.e. W/W%
• Here mass of solute is total mass of all the nitrogen atoms present in ammonium nitrate and mass of solvent equals to the mass of ammonium nitrate.
• Mass due to nitrogen = $28$ g/mol.
• Therefore, percentage nitrogen by weight = $\frac{28}{80}\times 100$= $35\%$

Thus, the percentage by weight of nitrogen in ammonium nitrate is $\mathbf{35}\mathbf{\%}$.