1. Warm -Up What is the name of the compound
with the chemical formula CrCl 3
A. chromium tetrachloride
B. chromium trichloride
C.chromium(II) chloride
D.chromium(III) chloride

2. Limiting Reactants
Why do reactions stop?
When one of the reactants is used up completely, the reaction stops

3. The reactant that is used up is called the LIMITING REACTANT (LR)
Limiting Reactants
The reactant that is used up is called the LIMITING REACTANT (LR)
The reactant that remains behind (or left over) is called the EXCESS REACTANT (ER)
A reaction cannot produce any more product that the limiting reactant will allow

4. Steps for Limiting Reactant
1) Determine the amount of product that each reactant produces
In other words, convert each of the givens to the same product
2) The reactant that produces the least amount of product is the limiting reagent

5. Example
Determine the amount of tetraphosphorus decoxide formed if 25.0 g of P4 and 50.0 g of O2 are combined.
P4 + 5 O2  P4O10

6. Practice
At high temperatures, sulfur combines with iron to form the brown-black iron (II) sulfide:
Fe (s) + S (l)  FeS (s)
In one experiment, 7.62 g of Fe are allowed to react with 8.67 g of S.
1)What is the limiting reactant, and what is the reactant in excess?
2) Calculate the mass of FeS formed.

7. More Practice
Arcylonitrile, C3H3N, is the starting material for the production of a kind of synthetic fiber and can be made from propylene, C3H6, by reaction with nitric oxide, NO, as follows:
4 C3H6 + 6 NO  4 C3H3N + 6 H2O + N2
What is the limiting reactant and what mass of C3H3N can be made when 21.6 g of C3H6 react with 21.6 g of nitric oxide?

8. Percent Yield
Percent Yield is the ratio of the actual yield to the theoretical yield expressed as a percent
% Yield =   mass of Actual Yield  x   100%
                    mass of Theoretical Yield        

9. Example:
In an experiment, 45.0 g of H2 are reacted with excess O2 to form water. A chemist collects 381 g of H2O. What is the percent yield?

10. Example 2:
In an experiment, 37.5 g of Na are reacted with excess F2 to form NaF. A chemist collects 58.2 g of NaF. What is the percent yield?
Stop Here