Question

The molar mass of Al is 27.0 g/mol.
The molar mass of S is 32.1 g/mol.
The molar mass of O is 16.0 g/mol.
Calculate the molar mass for the compound Al^2 (SO4)3 .

Answer 1

To calculate the molar mass of the compound \( \text{Al}_2(\text{SO}_4)_3 \), we will need to sum the molar masses of all the atoms in the formula.

The formula \( \text{Al}_2(\text{SO}_4)_3 \) contains:
- 2 aluminum (Al) atoms
- 3 sulfate (\( \text{SO}_4^{2-} \)) groups

First, let's break it down:

1. **Calculating the molar mass of Aluminum:**
- Molar mass of \( \text{Al} = 27.0 \, \text{g/mol} \)
- For 2 Al atoms: \( 2 \times 27.0 \, \text{g/mol} = 54.0 \, \text{g/mol} \)

2. **Calculating the molar mass of Sulfate (\( \text{SO}_4 \)):**
- Molar mass of Sulfur (S) = 32.1 g/mol
- Molar mass of Oxygen (O) = 16.0 g/mol
- For one sulfate group: \( 32.1 + 4 \times 16.0 = 32.1 + 64.0 = 96.1 \, \text{g/mol} \)
- For 3 sulfate groups: \( 3 \times 96.1 \, \text{g/mol} = 288.3 \, \text{g/mol} \)

3. **Total molar mass of \( \text{Al}_2(\text{SO}_4)_3 \):**
\[
54.0 \, \text{g/mol} + 288.3 \, \text{g/mol} = 342.3 \, \text{g/mol}
\]

Thus, the molar mass of \( \text{Al}_2(\text{SO}_4)_3 \) is **342.3 g/mol**.