Question

A compound contains 4.07% carbon and 71.65% clorine .its molecular mass is98.96.what are its imperical and molecular formula?

Answer 1

                Hydrogen          Carbon             Chlorine

       mass      4.07                 24.27                 71.65

       RAM         1                      12                     35.5

no. of moles  4.07/1               24.27/12            71.65/35.5

                      4.07                    2.02                2.02

divide by the   4.07/2.02          2.02/2.02         2.02

 least no            2                           1                 1

Empirical formula therefore is H2CCl

the molecular formula is (EF)n=MF

(1+1+12+35.5)=49.5......98.96/49.5=2  n=2

(H2CCl)2=H4C2Cl2

therefore the molecular formula is C2H4Cl2 (dichloroethane)