Which compound has the percent composition of 15.8% Al, 28.1% S and 56.1% O?

Question

Quizplus · Accepted Answer

Aluminum sulfate, $ \text{Al}_2(\text{SO}_4)_3 $, matches the given percent composition. The molar masses of Al, S, and O are approximately 27 g/mol, 32 g/mol, and 16 g/mol, respectively. In $ \text{Al}_2(\text{SO}_4)_3 $, there are 2 Al, 3 S, and 12 O atoms. The total molar mass is $ 2(27) + 3(32) + 12(16) = 342 $ g/mol. The percent compositions are calculated as follows: for Al, $ \frac{2(27)}{342} \times 100 \approx 15.8\% $; for S, $ \frac{3(32)}{342} \times 100 \approx 28.1\% $; and for O, $ \frac{12(16)}{342} \times 100 \approx 56.1\% $, matching the given values.

Which Compound Has the Percent Composition of 15