Question

Phenylenediamine consists of C,H, and N. The combustion of Phenylenediamine produces carbon dioxide, water, and nitrigen gas. when 12.570g of phenylenediamine was combusted, the products were 8.3764g of water and 3.2568g of nitrogen gas(with some carbon dioxide). What is the empirical formula of phenylenediamine?

Answer 1

mass of water = 8.3764 g

moles of water = 8.3764 / 18.02 = 0.4648

moles of H = 0.9296

mass of H = 0.9296 g

mass of N2 = 3.2568 g

moles of N2 = 3.2568 / 28 = 0.1163

moles of N = 0.2326

mass of N = 3.2564 g

mass of C = 12.570 - (3.2564 + 0.9296)

                = 8.384 g

moles of C = 0.6987

ratio :

       C        H        N

0.6987     0.9296    0.2326

       3              4            1

Emperical formula of phenylenediamine = C₃H₄N