Question

A compound consisting of b, n, and h undergoes elemental analysis. the % composition by mass is found to be 40.28% b, 52.20% n, and 7.53% h. what is the empirical formula for this molecule? enter in the empirical formula in the form bxnyhz.

Answer 1

To compute for the empirical formula, assume there is 100 grams of the compound. That means there is 40.28 g B, 52.2 g N and 7.53 g H. Convert the mass into moles using their molar masses:

40.28 g B * 1 mol/10.811 g = 3.725835 mol B
52.2 g N * 1 mol/14 g = 3.72857 mol N
7.53 g H * 1 mol/1 g = 7.53 mol H

Divide all the moles by the smallest amount which is 3.725835 mol.

B: 3.725835/3.725835 = 1
N: 3.72857/3.725835 = 1
H: 7.53/3.725835 = 2

Therefore, the empirical formula is BNH₂.