A compound of carbon, hydrogen, and nitrogen contains the three elements in the respective ratio of `9 : 1 : 3.5` Calculculate the empirical formula. If the molecular weight of the compound is 108, what its molecular formula?

Answer

B, C

Explanation

`C : H : N = 9 : 1 : 3.5`
Mole ratio `C : H : N = (9)/(12) : (1)/(1) : (3.5)/(14) = 0.75 : 1 : 10.25`
`= (0.75)/(0.25) : (1)/(0.25) : (0.25)/(0.25) = 3 : 4 : 1`
Empirial formula `= C_(3) H_(4) N`
Empirical formula weight `= C_(3) H_(4) N`
`12 xx 3 + 1 xx 4 + 14 = 54`
`Mw = 108`
`n = (Mw)/(EFw) = (108)/(54) = 2`
Molecular formula `= 2 xx C_(3) H_(4) N = C_(6) H_(8) N_(2)`