Can someone help me with this problem?

Question

White phosphorus, P4, is prepared by fusing calcium phosphate, Ca3(PO4)2, with carbon, C, and sand, SiO2, in an electric furnace.


2Ca3(PO4)2(s) + 6SiO2(s) + 10C(s) ==> P4(g) + 6CaSiO3(l) + 10CO(g)


How many grams of calcium phosphate are required to give 36.5 g of phosphorus?

Answer 1

Step 1. Divide 36.5 by the "mole wt" of P4, call result "A"
Step 2. From equation 2 moles of Ca-phosphate are required to make 1 "mole" of P4.
Step 3. Multiply 2A by the mole wt of calcium phosphate. That's your answer.

Answer 2

(36.5 g P4)(1 mol P4/123.892 g P4)(2 Ca3(PO4)2 mol/ 1 P4 mol)(310.181 g Ca3(PO4)2/1 mol Ca3(PO4)2) = 182.766 g of Ca3(PO4)2 required.

I hope thats what your looking for.