Limiting Reactants and Percent Yield

Definitions The Limiting Reactant is the reactant that limits the amounts of the other reactants that can combine and the amount of product that can form in a chemical reaction. Reactant run out of first. The excess reactant is the substance that is not used up in a reaction. Reactant we have left overs.

1engine + 4 tires → 1 car If you have two engines and seven tires which is your limiting reactant and which is in excess? 2 engines 1 engine 4 tires = 8 tires

Practice problem#1 SiO 2 + 4HF → SiF 4 + 2H 2 O If 2.0 moles of HF are exposed to 4.5 moles of SiO 2, which is the limiting factor? 2 mol HF 4 moles HF 1 mole SiO 2 = 0.5 moles SiO 2

Practice problems 2.N 2 H 4 + 2H 2 O 2 → N H 2 O a) Which is the limiting reactant in this reaction when 112g of N 2 H 4 is mixed with 125g of H 2 O 2 ? b)How much of each product could be produced, in grams?

Practice problems Pg.368 #21

Percent Yield The theoretical yield is the maximum amount of product that can be produced from a given amount of reactant. (The result of a mass-mass problem) The actual yield is the actual amount of a product obtained from a reaction.

When 36.8 g of C 6 H 6 react with excess Cl 2, the actual yield of C 6 H 5 Cl is 38.8g. What is the percent yield of C 6 H 5 Cl? C 6 H 6 + Cl 2 → C 6 H 5 Cl + HCl Do a mass-mass problem to determine your theoretical yield. Divide your actual yield by your theoretical yield and convert to percent. theoretical yield actual yield = 38.8g 53.0g =.732 x100 =73.2%