A pure oxide of lead (Pb) contains 13.4% of oxygen. calculate the empirical formula

Answer 1

Let's assume we start with 100 g of the lead oxide Pb_xO_y and then % will be equal to grams.

13.4% is O which means that 100% - 13.4% = 86.6% is Pb

Converting these to moles, we have...

13.4 g O x 1 mol O / 16 g = 0.8375 mols of O

86.6 g Pb x 1 mol Pb / 207 g = 0.4184 mols of Pb

Divide both by 0.4184 in order to try to get whole numbers:

O: 0.8375 / 0.4184 = 2.00

Pb: 0.4184 / 0.4184 = 1.00

The empirical formula = PbO₂