Question

A hydrated compound contains 25.9% calcium, 20.8% sulphur,41.6% oxygen and the rest is water of crystalization. Determine the empirical formula and give its IUPAC name

Answer 1

Let 100 gm of compound is taken

Then

Moles of Ca taken = $\frac{25.9}{40}=0.6475$

Moles of S taken = $0.65$

Moles of oxygen taken = $\frac{}{}$ $\frac{41.6}{16}=2.6$

Moles of water = $\frac{11.7}{18}=0.65$

Dividing all term by 0.65 for getting simple whole no. Ratio

We get,

Ratio of Ca : S : O : $H_2O$ = 1 : 1 : 4 : 1

So the compound is

$CaSO_4•H_2O$

IUPAC name = Calcium sulfate