Question

When iron reacts with oxygen, it forms iron oxide, or rust.

4 Fe + 3 O2 2 Fe2O3

If 112 g of iron (Fe) combines with 24 g of oxygen (O2), how much iron oxide is formed?

Answer 1

136 g Fe2O3

Step-by-step explanation:

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Answer 2

Mass of iron oxide: 79.85 g

Step-by-step explanation:

Given data:

Mass of iron = 112 g

Mass of O₂ = 24 g

Mass of iron oxide formed = ?

Solution:

4Fe + 3O₂ → 2Fe₂O₃

Number of moles of Fe:

Number of moles = mass/ molar mass

Number of moles = 112 g/ 55.85 g/mol

Number of moles = 2 mol

Number of moles of O₂:

Number of moles = mass/ molar mass

Number of moles = 24 g/ 32 g/mol

Number of moles = 0.75 mol

Now we will compare the moles of oxygen and iron with iron oxide.

Fe : Fe₂O₃

4 : 2

2 : 2/4×2 = 1

O₂ : Fe₂O₃

3 : 2

0.75 : 2/3×0.75 = 0.5

The number of moles of iron oxide formed by oxygen are less thus it will be limiting reactant.

Mass of iron oxide:

Mass = number of moles × molar mass

Mass = 0.5 mol × 159.69 g/mol

Mass = 79.85 g