Question

A compound has the empirical formula CH and a molar mass of 78.11 g/mol . Find its molecular formula.

Answer 1

Answer:

Molecular Formula = C6H6

Explanation:

Empirical Formular = CH

Molar Mass = 78.11

Molecular Formular = ?

The Formular relating these parameters is given as;

(Empirical Formula)n = Molecular Formular

where n = Number of moles

CH = 12.0107 + 1.00784 = 13.01854

(13.01854)n = 78.11

n = 78.11 / 13.01854

n = 5.9999 ≈ 6

Molecular Formula = C6H6

Answer 2

Answer:

C - 12.01 g/mol

H - 1.008 g/mol

CH - 13.018g/mol

molecular formula = n×(empirical formula)

       78.11 g/mol     = n ×( 12.01 + 1.008) g/mol

       ∴ n = 5.99

        ≈ 6

then $C_{6} H_{6}$

Explanation: First find the molar mass of the empirical formula CH.

use the formula that says: Molecular formula = n × empirical formula

therefore you divide the molar mass of the compound by molar mass of the empirical formula.

the empirical is the 6th and then multiply that 6 with the subscripts of CH.