Question

The empirical formula of a chemical substance is C2H3. The molar mass of a molecule of the substance is 54.091 g/mol. What is the molecular formula of the chemical substance?

Answer 1

Answer:- Molecular formula of the compound is $C_4H_6$ .

Solution:- An empirical formula and molar mass of the compound is given and we are asked to calculate it's molecular formula. First of all we calculate the empirical formula mass and then divide the molar mass by empirical formula mass to find out the number of empirical formula units.

Empirical formula is multiplied by the number of empirical formula units to get the molecular formula.

Empirical formula mass = 2(12.01) + 3(1.01)

= 24.02 + 3.03

= 27.05

number of empirical formula units = $\frac{54.091}{27.05}$

= 2

So, molecular formula of the compound = $2(C_2H_3)$

= $C_4H_6$