Calculate the mass of aluminum sulfide that is formed by the interaction of 10.8 grams of aluminum with sulfur.

2Al + 3S = Al2S3.

To solve this problem, we will use the data: Mr (Al) = 27 g / mol, Mr (Al2S3) = 150 g / mol.

Because from 2 moles of aluminum 1 mole of aluminum sulfide is formed, then it can be argued that from 2 * 27 g of aluminum, 150 g of sulfide is formed. Let’s make a proportion, from where we determine the desired mass of aluminum sulfide:

2 * 27 g – 150 g

10.8 g – x g.

Hence x = 10.8 * 150/2 * 27 = 30 g.