Answer to Question #113200 in Chemistry for Mohammed Al-fatlawi

Question

A 30g sample of ore contains 25g of haematite, Fe2O3. What mass of iron could be extracted?

Answer 1

As you can see from the molecular formula, there are 2 atoms of iron in one molecule of haematite Fe₂O₃. Therefore the number of the moles of hematite and the number of the moles of iron that can be extracted relate as:

$n(Fe_2O_3) = n(Fe)/2$ .

Let's calculate the number of the moles of haematite. Its molar mass $M$ is 159.69 g/mol:

$n(Fe_2O_3) = \frac{m}{M} = \frac{25}{159.69} = 0.157$ mol.

Then, the number of the moles of iron is:

$n(Fe) = 2·0.157 = 0.313$ mol.

The molar mass of iron is 55.84 g/mol. The mass of the iron that can be extracted:

$m(Fe) = n·M = 0.313·55.84 =17.5$ g

Answer: A 30g sample of ore contains 25g of haematite, Fe₂O₃. The mass of iron could be extracted is 17.5 g.