What is the mass percent of aluminum (Al) in aluminum sulfate, Al2(SO4)3?

• A. 28.11%
• B. 8.13%
• C. 15.79%
• D. 53.50%

Answer: (C)

Verified step by step guidance

1. Identify the chemical formula of aluminum sulfate: \(\mathrm{Al_2(SO_4)_3}\).
2. Calculate the molar mass of aluminum sulfate by summing the atomic masses of all atoms in the formula: multiply the atomic mass of aluminum (Al) by 2, sulfur (S) by 3, and oxygen (O) by 12 (since there are 4 oxygens per sulfate and 3 sulfate groups). The atomic masses are approximately: \(\mathrm{Al = 26.98\ g/mol}\), \(\mathrm{S = 32.07\ g/mol}\), and \(\mathrm{O = 16.00\ g/mol}\).
3. Calculate the total mass contributed by aluminum atoms: \$2 \times 26.98\ \mathrm{g/mol}$.
4. Calculate the total molar mass of aluminum sulfate by adding the masses of aluminum, sulfur, and oxygen calculated in step 2.
5. Find the mass percent of aluminum by dividing the total mass of aluminum by the molar mass of aluminum sulfate and multiplying by 100%: \(\text{Mass \% Al} = \left( \frac{2 \times 26.98}{\text{Molar mass of } \mathrm{Al_2(SO_4)_3}} \right) \times 100\%\).