What is the percentage of mass of A. Phosphorus in Ca3(PO4)2 B. Nitrogen in (NH4)3PO4?

Answer 1

Phosphorus in Ca3(PO4)2
Let's do this by common sense. If I gave you a basket containing 5 pounds of apples and 5 pounds of oranges and asked you to calculate percent apples and oranges I know you would say, "That's easy. It's 50% each, of course." And of course you would be right. BUT, how did you calculate that?
You said I have 5 pou

nds apples in a total of 10 pounds for both so (5 pounds apples/10 total) *100 = 50%. Chemicals don't make it any different so treat it the same way. For part A, it is (mass P/total mass)*100 = % P
[(2*atomic mass P)/(total mass Ca3(PO4)2]*100 = ?
Part B is worked the same way.