Question: how to calculate mass percent of oxygen in potassium chlorate?
Answer: Procedures: 1. ...  mass of oxygen driven off___ x 100 = experimental percentage of oxygen in mass of potassium chlorate used KClO3 0.74 g x 100 = 37.6 % 3 mol O x 16.00 g/mol x 100 = 39.17 % 122.55 g/mol. valueaccepted 0.772 g – 0.74 g x 100 = 4.14% 0.772 g.