What is limiting reactant in chemistry?

Limiting/excess reactant problem for IDEAL GAS LAW? ap chemistry problem HELP?

• a. P4+6F2=4PF3 in this balanced reaction, P4 AND 6F2 form 4PF3. 10.87g of P4 and 2.98L of F2 react. The pressure is 1.15 atm and the temperature 20 C. What is the limiting reactant? Excess reactant? Mass of excess reactant remaining?

• Answer:

  P4 + 6 F2 → 4 PF3 (10.87g P4) / (123.895 g P4/mol) = 0.0877356 mol P4 (2.98 L F2) x (1.15 / 1.00) x (273 / (20 + 273)) / (22.414 L/mol) = 0.14246 mol F2 0.14246 mole of F2 would react completely with 0.14246 x (1/6) = 0.023743 mole of P4, but there is more P4 present than that, so P4 is in excess and F2 is the limiting reactant. ((0.0877356 mol P4 initially) - ( 0.023743 mol P4 reacted)) x (123.895 g P4/mol) = 7.93 g P4 left over