Question

An oxide of iron has 69.9% iron and 30.1% oxygen by mass. How much Fe is present in 12 g of oxide?​

Answer 1

Answer:

 The iron oxide has 69.9% iron and 30.1% dioxygen by mass.

Thus, 100 g of iron oxide contains 69.9 g iron and 30.1 g dioxygen.

The number of moles of iron present in 100 g of iron oxide are 55.869.9=1.25.

The number of moles of dioxygen present in 100 g of iron oxide are 3230.1=0.94.

The ratio of the number of oxygen atoms to the number of carbon atoms present in one formula unit of iron oxide is 1.252×0.94=1.5:1=3:2.

Hence, the formula of the iron oxide is Fe2O

Answer 2

12 g oxide contains 8.388 g of Iron.

Given,

An oxide of iron has 69.9% iron and 30.1% oxygen by mass.

To Find,

How much Fe is present in 12 g of oxide

Solution,

Let the mass of oxide taken to be 100 g

In 100 g of oxide, 69.9 g of iron is present as per the given information

Now by unitary method -

100 g oxide contains → 69.9 g of iron

1 g oxide contains → $\frac{69.9}{100}$ g of iron

12 g oxide contains → $\frac{69.9}{100}*12$ g of iron

Mass of Fe contained in 12 g oxide =  $\frac{69.9}{100}*12$ g

Mass of Fe contained in 12 g oxide =  $0.699*12$ g

Mass of Fe contained in 12 g oxide = 8.388 g

Hence, 12 g oxide contains 8.388 g of Iron.

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