Determine the empirical formula for a compound that contains 35.98% aluminum and 64.02% sulfur?

Al2S3

Explanation:

Firstly, we need to know their atomic masses. The atomic mass of sulphur is 32 while that of aluminum is 27.

So firstly, we divide the percentage compositions with their atomic masses.

S = 64.02/32 = 2.000625

Al = 35.98/27 = 1.3326

We then proceed to divide each by the smallest of the two.

S = 2.000625/1.3326 = 1.5

Al = 1.3326/1.3326 = 1

Let's multiply each by 2 to yield 3 and 2 respectively.

The empirical formula is thus Al2S3