Question

If a particular ore contains 55.4% calcium phosphate, what minimum mass of the ore must be processed to obtain 1.00kg of phosphorus?

Answer 1

First, we require the formula of calcium phosphate. This is:
Ca₃(PO₄)₂

And its mass is 310 g/mol

The atomic mass of phosphorus is 31 g/mol, and as there are 2 moles of P per mole of calcium phosphate, the mass of P is 62 g/ mol calcium phosphate

Now, we calculate the percentage mass of phosphorus in calcium phosphate. This is:
62/310 * 100 = 20%

So, if we need 1 kg of P, we need:

1/20% = 5 kg of calcium phosphate. This means we need:

5 / 55.4% = 9.02 kg of ore


9.02 kg of ore is required.