Question

A hydride of nitrogen contains 87.5 percent by mass of nitrogen .determine the empirical formula of this compound.

Answer 1

Dear student,

Constituents	Symbol	%age	Atomic mass	moles of the element = %age/at. mass (relative no. of moles)	Simplest molar ratio	Simplest whole no. ratio
Nitrogen	N	87.5	14	87.5/14=6.25	6.25​/6.25​=1	1
Hydrogen	H	12.5	1	12.5/6.25=4.34	12.5/6.25=2	2

Thus, empirical formula (NH₂)

But nitrogen forms trivalent compound so hydride of nitrogen by 87.5 by mass % is N₂H₄ ( dimer of NH₂).

Regards