Question

calculate the percent composition of magnesium nitrate

Answer 1

To calculate the percent composition of magnesium nitrate \((\text{Mg(NO}_3\text{)}_2)\), we first need to determine the molar mass of the compound and the contribution of each element to that mass.

1. **Molar Mass Calculation**:
- Magnesium (Mg): 24.31 g/mol
- Nitrogen (N): 14.01 g/mol
- Oxygen (O): 16.00 g/mol

Now we can calculate the molar mass of magnesium nitrate:

\[
\text{Molar mass of Mg(NO}_3\text{)}_2 = (\text{1 Mg} \times 24.31 \, \text{g/mol}) + (\text{2 N} \times 14.01 \, \text{g/mol}) + (\text{6 O} \times 16.00 \, \text{g/mol})
\]

Calculating each part:

- For magnesium: \( 1 \times 24.31 = 24.31 \, \text{g/mol}\)
- For nitrogen: \( 2 \times 14.01 = 28.02 \, \text{g/mol}\)
- For oxygen: \( 6 \times 16.00 = 96.00 \, \text{g/mol}\)

Now sum these values to find the total molar mass:

\[
\text{Total molar mass} = 24.31 + 28.02 + 96.00 = 148.33 \, \text{g/mol}
\]

2. **Percent Composition Calculation**:
Now we can find the percent composition by dividing the mass contribution of each element by the total molar mass and multiplying by 100.

- **Percent of Magnesium**:
\[
\text{Percent of Mg} = \left( \frac{24.31}{148.33} \right) \times 100 \approx 16.40 \%
\]

- **Percent of Nitrogen**:
\[
\text{Percent of N} = \left( \frac{28.02}{148.33} \right) \times 100 \approx 18.88 \%
\]

- **Percent of Oxygen**:
\[
\text{Percent of O} = \left( \frac{96.00}{148.33} \right) \times 100 \approx 64.72 \%
\]

3. **Summary of Percent Composition**:
The percent composition of magnesium nitrate \((\text{Mg(NO}_3\text{)}_2)\) is approximately:
- Magnesium: **16.40%**
- Nitrogen: **18.88%**
- Oxygen: **64.72%**