Question

A compound contains 28 percent of nitrogen and 72 percent of a metal by weight. 3 atoms of the metal combine with 2 atoms of N. Find the atomic weight of the metal.

Answer 1

3 atoms of metal (M ) combines with 2 atoms of nitrogen,

Thus, the formula of compound  =  M₃N₂

Equivalent wt. of nitrogen = 14/3 

:. 28 g nitrogen combines with 72 g metal 

1 g nitrogen combines with = 72/28 g metal

14/3 g  nitrogen combines with metal = 72/28 x 14/3 g = 12 g

As valency of  metal  = 2

 Atomic weight = 2 x equivalent weight

= 2 x 12

= 24 g