Warm-up 2 O2 + N2 2 NO2 • 205 grams N2 = ___________ grams NO2 • 315 grams O2 = ___________ grams NO2
Stoichiometry:Limiting Reactants Unit Seven, Day Three Kimrey 14 November 2012
What is a limiting reactant? • The limiting reactant is the reactant that determines the amount of the product produced. • The reactant that runs out first.
Real world example • A typical PBJ contains 2 slices of bread, 9 tablespoons of peanut butter, and 4 tablespoons of jelly. • If you were given the following, how many sandwiches could you make using the above recipe? • Given: • 38 slices of bread • 22 Tbs peanut butter • 12 Tbs jelly
Applying this to Chemistry • Use both the givens and solve for the problem • Compare the answers the smaller value is the correct answer and the given that gave you that answer is called the limiting reactant. • The other reactant is called the excess reactant
Example 2 AgNO3 + CaCl2 2AgCl + Ca(NO3)2 • If a solution containing 20.0 grams of silver nitrate is mixed with a solution containing 10.0 grams of calcium chloride, how many grams of silver chloride will be produced? What is your limiting reactant? What is your excess reactant?
Which is the limiting reactant? • If you’re given the formula and quantities of each reactant: • Using what you’re given for each reactant, just pick one of the products and determine how many moles you would get • Whichever reactant gives you the smallest number of moles is the limiting reactant • The other reactant is the excess reactant • This way will only tell you which reactant is the limiting one, it won’t tell you how much product will be produced!
Example C6H12 + 9 O2 6 CO2 + 6 H2O • Which of the reactants will be the limiting reactant if 105 grams of C6H12 are mixed with 57.0 grams of O2?