Ammonia (NH3) chemically reacts with oxygen gas (O2) to produce nitric oxide (NO) and water (H2O).

What mass of water is produced by the reaction of 3.58 g of ammonia?
Be sure your answer has the correct number of significant digits.

1 answer

To determine the mass of water produced by the reaction of 3.58 g of ammonia (NH3), we need to follow these steps:

1. **Write the balanced chemical equation for the reaction:**

\[
4 \text{NH}_3 + 5 \text{O}_2 \rightarrow 4 \text{NO} + 6 \text{H}_2\text{O}
\]

2. **Calculate the molar mass of NH3:**

- Nitrogen (N): 1 atom × 14.01 g/mol = 14.01 g/mol
- Hydrogen (H): 3 atoms × 1.008 g/mol = 3.024 g/mol

\[
\text{Molar mass of NH}_3 = 14.01 \text{g/mol} + 3.024 \text{g/mol} = 17.034 \text{g/mol}
\]

3. **Convert the mass of NH3 to moles:**

\[
\text{Moles of NH}_3 = \frac{3.58 \text{ g}}{17.034 \text{ g/mol}} = 0.210 \text{ mol}
\]

4. **Use the stoichiometric coefficients from the balanced equation to find the moles of water produced:**

According to the balanced equation, 4 moles of NH3 produce 6 moles of H2O. Therefore, the ratio is:

\[
\frac{6 \text{ moles H}_2\text{O}}{4 \text{ moles NH}_3} \rightarrow \text{For every mole of NH}_3, \, \frac{6}{4} = 1.5 \text{ moles H}_2\text{O}
\]

5. **Calculate the moles of H2O produced from the given moles of NH3:**

\[
\text{Moles of H}_2\text{O} = 0.210 \text{ mol NH}_3 \times 1.5 \text{ mol H}_2\text{O / mol NH}_3 = 0.315 \text{ mol H}_2\text{O}
\]

6. **Calculate the mass of H2O produced:**

The molar mass of H2O is:

- Hydrogen (H): 2 atoms × 1.008 g/mol = 2.016 g/mol
- Oxygen (O): 1 atom × 16.00 g/mol = 16.00 g/mol

\[
\text{Molar mass of H}_2\text{O} = 2.016 \text{g/mol} + 16.00 \text{g/mol} = 18.016 \text{g/mol}
\]

\[
\text{Mass of H}_2\text{O} = 0.315 \text{ mol} \times 18.016 \text{ g/mol} = 5.67 \text{ g}
\]

Therefore, the mass of water produced by the reaction of 3.58 g of ammonia is **5.67 g**. This answer is reported to three significant digits to match the precision of the given mass of ammonia.