Question

Empirical formula of a compound is C₂H₅ and its molecular weight is 58, then its molecular formula is __________.

Answer 1

Relationship between empirical formula and molecular formula is given as follows:

Molecular formula= n× Empirical formula

$n=\frac{Molecularweightofthecompound}{Empiricalformulaweight}$

Given: Molecular weight= 58 u

Empirical formula weight is obtained by the addition of the atomic weight of the various atoms present in the empirical formula.

Empirical formula weight of C₂H₅ = 2(Atomic weight of Carbon)+ 5(Atomic weight of Hydrogen)

Empirical formula weight of C₂H₅ = 2(12)+ 5(1)

Empirical formula weight of C₂H₅ =24+5= 29 u

Therefore, $n=\frac{58}{29}=2$

As, Molecular formula= n× Empirical formula and empirical formula is C₂H_5.

The molecular formula =(C₂H₅)₂ =C₄H₁₀

Therefore, if empirical formula of a compound is C₂H₅ and its molecular weight is 58, then its molecular formula is C₄H₁₀.