Question

a compound has a molar mass of 129 g/mol if its empirical formula is C2H5N then what is the molecular formula

Answer 1

Given :

A compound has a molar mass of 129 g/mol .

Empirical formula of compound is C₂H₅N .

To Find :

The molecular formula of the compound.

Solution :

Empirical mass of compound :

$M_e = ( 2 \times 12 ) + ( 5 \times 1 ) + ( 1 \times 14 )\\\\M_e = 43\ gram/mol$

Now, n-factor is :

$n = \dfrac{M}{M_e}\\\\n = \dfrac{129}{43}\\\\n = 3$

Multiplying each atom in the formula by 3 , we get :

Molecular Formula, C₆H₁₅N₃