Question

Calculate the molecular formula of compound which contains 20% Ca and 80% Br (by wt.) if molecular weight
of compound is 200.

Answer 1

assume the mixture to be 100
mole of Ca =20/40=1/2
mole of Br =80/80=1
ratio between Ca and Br =1/2
or, 1:2
it means Ca1Br2
so empirical formula becomes CaBr2

Answer 2

Answer:

The molecular formula is $\bold{C a B r_{2}}$

Explanation:

Given:

A compound as molecular formula of 20% of Ca and 80% of Br.

To find:

Molecular weight of compound when it is 200.

Let us assume the mixture formed to be as 100.

Now let us find the mole of Ca and Br separately.

Mole of Ca

=20/40

=1/2

Mole of Br  

=80/80

=1

The ratio between Ca and Br is given by 1:2 that is $C a_{1} B r_{2}$

Therefore empirical formula = $C a B r_{2}$