Question

A compound with the empirical formula C2HF4 was found to have a molar mass of about 200g/mole. What is the molecular formula of the compound?

Answer 1

Answer:

$C_4H_2F_8$ is the molecular formula of the compound.

Explanation:

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is :

$n=\frac{\text{molecular mass}}{\text{empirical mass}}$

We are given:

Mass of molecular formula = 200 g/mol

Mass of empirical formula of $C_2HF_4$ :

2 × 12 g/mol + 1 × 1 g/mol + 4 × 19 g/mol = 101 g/mol

Putting values in above equation, we get:

$n=\frac{200 g/mol}{101 g/mol} =1.9 \approx 2$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(2\times 2)}H_{(1\times 2)}F_{(4\times 2)}=C_4H_2F_8$

$C_4H_2F_8$ is the molecular formula of the compound.