So today we did some stuff about percent yield. It is a ratio of amount of product obtained to amount of product expect. Let's simplify it, which is the grams of product recovered divided by the grams of product expected from stoichiometry. Then multiply the results by 100%. We also did something called percent purity, it is the ratio of mass of pure substance to mass of impure expressed in a percent. Which is mass of pure substance divided by mass of impure substance and multiply the results by 100%.
http://www.youtube.com/watch?v=TKNxdL7DN1I