What is the empirical formula of a compound that contains 32.39 percent sodium 22.53 percent sulfur and 45.07 percent oxygen?

First assume you have 100 g of the substance & then convert to moles using the molecular weight of each element:

Na: 32.39 g / (22.99 g/mol) = 1.409 mol Na

S : 22.53 g / (32.07 g/mol) = 0.703 mol S

O : 45.07 g / (16.00 g/mol) = 2.817 mol O

Next divide each mole amount by the smallest one of the group, in this case sulfur. This gives you the ratio of each element in the compound.

Na: 1.409 mol / 0.703 mol = 2.00

S : 0.703 mol/0.703 mol = 1.00

O: 2.817 mol/0.703 mol = 4.01

Round to the nearest whole number & you get the formula: Na2SO4 (sodium sulfate)