Question

What is the percent by mass of sulfur in Al 2(SO₄)₃?

A. 9.38%
B. 18.8%
C. 24.6%
D. 28.1%
E. 35.4%

Answer 1

The percent by mass of sulfur in Al2(SO4)3 is calculated by dividing the mass of sulfur in the compound by the molar mass of the compound and then multiplying by 100%. The result is approximately 28.1%, which is option D.

Step-by-step explanation:

To calculate the percent by mass of sulfur in aluminum sulfate, Al2(SO4)3, we need to use the molar mass of the compound and the molar mass of sulfur (32 g/mol). The compound consists of 2 aluminum atoms, 3 sulfur atoms, and 12 oxygen atoms. The molar mass of Al2(SO4)3 is 342.14 amu.

First, we calculate the total mass of sulfur in the compound:

• Mass of sulfur = 3 atoms × 32 g/mol = 96 g/mol.

Next, we find the percent by mass:

• Percent by mass of sulfur = (Mass of sulfur / Molar mass of compound) × 100%.
• Percent by mass of sulfur = (96 g/mol / 342.14 g/mol) × 100% ≈ 28.1%.

Therefore, the percent by mass of sulfur in Al2(SO4)3 is approximately 28.1%, which corresponds to option D.