Question

What is the percentage composition of nitrogen in ammonium nitrate (\( \text{NH}_4\text{NO}_3 \))?

• A. 18.5%
• B. 28.0%
• C. 35.0%
• D. 42.5%

Hint:

Remember: To find the percentage composition of an element in a compound, divide the total mass of that element by the molar mass of the compound and multiply by 100.

Answer 1

The Correct Option is A

Step 1: Calculate the molar mass of ammonium nitrate The molecular formula of ammonium nitrate is \( \text{NH}_4\text{NO}_3 \). The molar masses of nitrogen (N), hydrogen (H), and oxygen (O) are: - Nitrogen (N) = 14 g/mol, - Hydrogen (H) = 1 g/mol, - Oxygen (O) = 16 g/mol. The molar mass of \( \text{NH}_4\text{NO}_3 \) is: \[ M_{\text{NH}_4\text{NO}_3} = (1 \times 14) + (4 \times 1) + (1 \times 14) + (3 \times 16) = 14 + 4 + 14 + 48 = 80 \, \text{g/mol} \] Step 2: Calculate the mass of nitrogen in ammonium nitrate There are two nitrogen atoms in \( \text{NH}_4\text{NO}_3 \), so the mass of nitrogen is: \[ \text{Mass of nitrogen} = 2 \times 14 = 28 \, \text{g/mol} \] Step 3: Calculate the percentage composition of nitrogen The percentage composition of nitrogen is: \[ \text{Percentage of nitrogen} = \left( \frac{\text{Mass of nitrogen}}{\text{Molar mass of NH}_4\text{NO}_3} \right) \times 100 = \left( \frac{28}{80} \right) \times 100 = 35\% \] Answer: Therefore, the percentage composition of nitrogen in ammonium nitrate is \( 35.0\% \). So, the correct answer is option (3).