Question

an organic compound on analysis is found have the following composition. Carbon=41.4%, hydrogen=5.75%, nitrogen=16.08% and the rest is oxygen. find out the empirical formula of the compound

Answer 1

Consider the total mass of compound is 100 g
Mass of element in 100 g of compound is equal to mass % of element.
Number of moles = mass / molar mass of element

Mass %	Moles of atom(% of mass/atomic mass)	simplest mole ratio
Carbon 41.4%	41.4 /12 = 3.45	3.45/1.14≈ 3
Hydrogen 5.75 %	5.75/1 =5.75	5.75/1.14≈ 5
Nitrogen 16.08 %	16.08/14=1.14	1.14/1.14=1
Oxygen 36.77 %	36.77/16=2.29	2.29/1.14≈ 2

Thus empirical formula of a compound is C₃H₅NO₂