Limiting Reagent?

Question

Phosphorus reacts with sulfur to produce a smelly, yellow crystalline solid, P2S5.
Show calculations.
a) Write a balanced chemical equation to represent this reaction
b) If 3.20g of phosphorus react with 4.10g of sulfur, which reactant is in excess?

Answer 1

2P + 5S ==> P2S5
Balanced equation
3.2g of P = 3.2/30.97molar mass= 0.103 mol
4.1g of S = 4.1/32.065molar mass= 0.128 mol
and in your balanced equation you have a 2:5 ratio where 2 moles of phorphorus react with 5 moles of Sulfur.
Therefore you have excess of phorphorus and a limit of Sulfur since you have 0.103 mol of P and its a 2:5 ratio with the Sulfur which only has 0.128 mol