Empirical formula is the simplest ratio of whole numbers of components making up the compound
Mass percentage of boron - 81.1 %
Mass percentage of hydrogen - 18.9 %
For 100 g of the compound
B H
Mass 81.1 g 18.9 g
Number of moles 81.1 g /11 g/mol 18.9 g/1 g/mol
= 7.37 mol = 18.9 mol
Divide by the least number of moles
7.37/7.37 =1.00 18.9/7.37 =2.56
Since we get 2.56 that cannot be rounded off we have to multiply both boron and hydrogen values by 2
B = 1.00 x2 = 2.00
H = 2.56 x 2 = 5.12 rounded off to 5
Therefore empirical formula is
B₂H₅
