Question

a compound has the following composition: C=85.7% and H=14.3%. if the molecular mass of the compound is 28, find the molecular formula. give the IUPAC name of the compound and write it's structural formula​

Answer 1

100 a.m.u of compound will contain 85.7 a.m.u C and 14.3 a.m.u H.

42 a.m.u (1 mole) of the compound will contain

100

42×85.7

=36 a.m.u C and

100

42×14.3

=6 a.m.u H.

The atomic masses of C and H are 12 a.m.u and 1 a.m.u respectively.

The number of moles of C present in 1 mole of compound =

12

36

=3 moles.

The number of moles of H present in 1 mole of compound =

1

6

=6 moles.

Hence, the molecular formula of the compound is C

3

H

6

.

The empirical formula of the compound is obtained by dividing molecular formula with 3. It is CH

2

.