Percent by Mass
Calculate the percent by mass of phosphorus and chlorine in phosphorus trichloride (PCl3).
- Assume one mole of phosporus trichloride. Find the moles of phosphorus and
moles of chlorine.
(1 mol PCl3) (1 mol P/ 1 mol PCl3) = 1 mol P
(1 mol PCl3) (3 mol Cl/ 1 mol PCl3) = 3 mol Cl
- Convert mole of each element to mass of each element.
- Calculate the percent by mass of each element.