Chemistry Question 02

Question

In 1860, Robert Boyle was the first to use phosphorus to ignite sulfur-tipped wooden splints that gave rise to our modern matches. One of the ways it can be made involves the chemical reaction of calcium phosphate with silicon dioxide and carbon in a furnace:

 

2Ca₃(PO₄)₂ + 6SiO₂ + 10C → 6CaSiO₃ + P₄ + 10CO

Refer to the information above. If you use 100.0 grams of calcium phosphate (Ca₃(PO₄)₂) and an excess of silicon dioxide and carbon, how many moles of phosphorus (P₄) will be produced?

A. - 0.1612 moles

B. - 0.3224 moles

C. - 15510 moles ( incorrect... )

D. - 1.551 moles

Please explain your answer!

Answer 1

The first thing necessary to do is to calculate the molar mass of Ca₃(PO₄)₂ to find to number of moles used in the reaction.

1. [3(40.08) + 2(30.9738+63.9976)] = 310.1828 g/mol
2. Then, 100g/ 310.1828g/mol = 0.3223905387 moles Ca₃(PO₄)₂ used in the reaction.
3. Finally, use the stoichiometric ratio between Ca₃(PO₄)₂ and P₄ to calculate moles of P₄
4. (0.3223905387 moles Ca₃(PO₄)₂ ) (1/2) = 0.1611952694 moles P₄ created.
5. ANSWER: 0.1612 moles