What is the molar mass of Al_2(SO_4)_3?

• A. 342.15 g/mol
• B. 294.18 g/mol
• C. 318.21 g/mol
• D. 278.02 g/mol

Answer: (A)

Verified step by step guidance

1. Identify the chemical formula given: Al_2(SO_4)_3, which means the compound contains 2 aluminum (Al) atoms, 3 sulfate (SO_4) groups.
2. Determine the atomic masses of each element involved from the periodic table: Aluminum (Al) ≈ 26.98 g/mol, Sulfur (S) ≈ 32.07 g/mol, Oxygen (O) ≈ 16.00 g/mol.
3. Calculate the molar mass of one sulfate ion (SO_4): sum the atomic masses of 1 sulfur atom and 4 oxygen atoms using the formula \(M_{SO_4} = M_S + 4 \times M_O\).
4. Multiply the molar mass of the sulfate ion by 3 because there are three sulfate groups: \$3 \times M_{SO_4}$.
5. Add the total mass of aluminum atoms (2 atoms) to the total mass of sulfate groups to get the molar mass of Al_2(SO_4)_3: \(M_{Al_2(SO_4)_3} = 2 \times M_{Al} + 3 \times M_{SO_4}\).