Question

How many moles of fe2o3 will be produced from 18.0 g of fe assuming o2 is available in excess

Answer 1

Answer:

0.161moles

Explanation:

Given parameters:

Mass of Fe  = 18g

Oxygen gas is in excess

Unknown:

Number of moles of Fe₂O₃ produced  = ?

Solution:

To start with, let us write a chemically balanced equation before proceeding to understand the nuances of this problem.

              4Fe       +    3O₂       →          2Fe₂O₃

In the equation above above, 4 mole of iron combined with 3 moles of oxygen gas to  2 moles of Fe₂O₃.

In solving this problem, we can identify that Fe is the limiting reactant since we have been told oxygen gas is in excess. The suggests that the extent to which the product is formed and the reaction proceeds hinges on the amount of Fe we have.

It is best to work from the given, or known reactant to the unknown

The known in this scenario is the mass of Fe. Let us find the number of moles of this specie;

        Number of moles of Fe  = $\frac{mass}{molar mass}$

              Molar mass of Fe  = 56g/mol

      Number of moles  = $\frac{18}{56}$   = 0.32mol

Using this known number of moles of Fe, we can relate it to that of the unknown amount of the product and obtain the number of moles.

           4 moles of Fe produced 2 moles of Fe₂O₃

         0.32 moles of Fe will produce $\frac{0.32 x 2}{4}$   =  0.161moles