Question

A certain compound contains 4.0 g of calcium and 7.1 g of chlorine. Its relative molecular mass is 111. Find its empirical and molecular formulas

Answer 1

Given :

A certain compound contains 4.0 g of calcium and 7.1 g of chlorine.

Its relative molecular mass is 111.

To Find :

Its empirical and molecular formulas.

Solution :

Moles of calcium ,
`n_1=(4)/(40)=0.1\ moles`.

Moles of chlorine ,
`n_2=(7.1)/(35.45)=0.2\ moles` .

The ratio calcium and chlorine is 1 : 2 .

So , the empirical formula is
`CaCl_2` .

Now , molecular mass of
`CaCl_2` is :

`M=40+(2* 35.45)\\\\M=110.9\ g`

So ,
`n=(111)/(110.9) \approx1`

Therefore , the molecular formula is also
`CaCl_2` .

Hence , this is the required solution .