Extra Stoichiometry Practice

1. How many grams of aluminum oxide can be formed by the reaction of 38.8 g of aluminum with

oxygen?

4 Al (8) + 3 O2 (g) →2 A12O (s)

Answer: 50. 4g

Explanation:

First calculate number of moles of aluminium in 38.8g

Moles = 38.8g / 26.982mol/g

= 1.44mol

By looking at the balance equation you can see that 4 moles of aluminium produce 2 moles of aluminium oxide.

4 = 2

1.4 = x

Find the value of x

x = (1.4*2) / 4 = 0.72 mol

0.72 moles of aluminium oxide are produced from 38.8g of aluminium

Now find the mass of aluminium produced.

Mass = moles * molar mass

= 0.72mol * 69.93 mol/g

= 50.4g