Question

How many moles of al2o3 will be formed when a mixture of 5.4 g of al and 3.2 g of o2 is heated?

Answer 1

Answer:

0.66 moles

Explanation:

This is a question on moles

We first write the correct chemical equation

4Al + 3O2 —> 2Al2O3

We the n get the moles of the reactants

    Oxygen

       Moles = mass/molar mass

         Mass is 3.2 g

          Molar mass is 16 × 2 = 32 the relative molecular mass of oxygen is 16

             3.2 ÷ 32 = 0.1 moles

     Aluminium

         Mass of Al is 5.4 g

          The relative molecular mass is 27

           Therefore 5.4 ÷ 27 = 0.2 moles

We then proceed to find the limiting reactant by diving moles of the reactants with the stoichiometric  Equivalents

0.1 ÷ 3 = 0.03

0.2 ÷ 2 = 0.1

Since the value of oxygen is lower than that of aluminium oxygen is the limiting factor

The mole ratio of oxygen to aluminium oxide is

3:2

Therefore

2 × 0.1 ÷ 3 = 0.66 moles

Answer 2

Explanation:

0.66 mole al2o3 will be formed when a mixture of 5.4 g of al and 3.2 g of o2 is heated