Question

A compound contains 87.5% by mass of nitrogen and 12.5% by mass of hydrogen. Determine the empirical formula of this compound.

Answer 1

Element	Atomic mass	Percentage	Relative number of moles	Simplest mole ratio	Whole number ratio
N	14	87.5	$\frac{87.5}{14}=6.25$	$\frac{6.25}{6.25}=1$	1
H	1	12.5	$\frac{12.5}{1}$	$\frac{12.5}{6.25}=2$	2

Therefore, empirical formula of this compound is NH₂.