1. Limiting Reactant & Percent Yield
Section 12-3
Limiting Reactant
&
Percent Yield

2. Limiting Reactant
A limiting reactant is the reactant that limits the amount of product that may be produced.
The quantities of product are always determined or controlled by the limiting reactant.
The reactant that produces the least amount of product through a stoichiometry problem (mass-mass, mass-volume, volume-volume) is the limiting reactant.

3. Limiting Reactant Let’s use a sandwich analogy
2 bread + 1 meat  1 sandwich
How many sandwiches can we make with 2 bread and 4 meat?

4. Limiting Reactant
Identify the limiting reactant when 1.7g of sodium reacts with 2.6L of chlorine gas at STP to produce sodium chloride.
Identify the limiting reactant when 10.0g of water reacts with 4.5g of sodium to produce sodium hydroxide and hydrogen gas.

5. Limiting Reactant
How can we determine we are dealing with a limiting reactant problem?
1) It asks for the limiting reactant.
2) There are two given amounts of reactants.

6. Limiting Reactant
How do we know we ARE NOT dealing with a limiting reactant problem?
1) In the word problem there is only one given amount.
2) The tell you the reaction runs to COMPLETION
3) They tell you there is one reactant in EXCESS.

7. Percent Yield Remember, Percent yield is where it’s A/T
% Yield = actual yield (A)/theoretical yield (T) x 100
%=A/T x 100
Actual yield is what you get in the lab
Theoretical yield is what we get in out mathematical stoichiometry problem.