Question

What is the molecular formula of the compound with a molecular weight of 112 g/mol and percent composition: 85.6% C and 14.4% H?

Select one:
a. C2H4
b. CH2
c. C4H8
d. C8H16

Answer 1

Molecular formula = C₈H₁₆

Step-by-step explanation:

Given data:

Percentage of hydrogen = 14.4%

Percentage of carbon = 85.6%

Molecular formula = ?

Molecular weight = 112 g/mol

Solution:

Number of gram atoms of H = 14.4/ 1.01 = 14.26

Number of gram atoms of C = 85.6/ 12 = 7.13

Atomic ratio:

C : H

7.13/7.13 : 14.26/7.13

1 : 2

C : H = 1 : 2

Empirical formula is CH₂

Molecular formula:

Molecular formula = n (empirical formula)

n = molar mass of compound / empirical formula mass

n = 112 / 14

n = 8

Molecular formula = n (empirical formula)

Molecular formula = 8 (CH₂)

Molecular formula = C₈H₁₆