Question

In a certain compound of iron and oxygen, FexOy, it is found that a sample of this compound weighing 6.285 g contains 4.396 g of Fe. What is the formula of the oxide?

Answer 1

Answer:

Formula of oxide is $Fe_{2}O_{3}$

Explanation:

The given compound consists of Fe and O.

So, mass of oxygen in sample = (mass of sample) - (mass of Fe in sample)

                                                   = (6.285 g ) - (4.396 g)

                                                   = 1.889 g

Molar mass of O = 16 g/mol and molar mass of Fe = 55.845 g/mol

So, ratio of number of moles of Fe and O (Fe : O)

      = $\frac{4.396}{55.845}:\frac{1.889}{16}$

      = 0.0787 : 0.118

      = $1:\frac{0.118}{0.0787}$

      = 1 : 1.5

      = 2 : 3

So, formula of oxide is $Fe_{2}O_{3}$