1. K. Knippel Chemistry Aldine HS
Limiting Reactants
K. Knippel
Chemistry
Aldine HS

2. S’Mores…yummmm How many S’Mores can I make with…? 6 graham crackers
8 pieces of chocolate
10 marshmallows
4 pieces of chocolate
What ingredient is limiting my number of
s’ mores????

3. Another demo- magnesium strip, boys to girls…

4. Limiting Reactant
In a chemical reaction, one reactant will run out before the other. We call this the limiting reactant.
The limiting reactant determines how much product will be created.
What were the limiting reactants with the s’mores??

5. In chemical reactions…
These chemical reactions we have been studying have limiting reactants as well.
Look at this reaction:
C + O2  CO2
2 carbon atoms +  +
3 carbon dioxide molecules
5 carbon atoms
3 oxygen molecules

6. SiO2 + 4HF  SiF4 + 2H2O
If 2.0 mol of HF are exposed to 4.5 mol of SiO2, which is the limiting reactant?
Balance
List what you know
Choose 1 product to find mols/grams for
Reactant that gives the least product is limiting reactant

7. SiO2 + 4HF  SiF4 + 2H2O 4.5 2.0 ? mol mol mol
2.0 mol HF 1 mol SiF = 0.50 mol SiF4 *least
mol HF
4.5 mol SiO mol SiF4 = 4.50 mol SiF4
mol SiO2

8. __Fe + __H2O  __Fe3O4 + __4H2
When 36.0g of H2O is mixed with 167g of Fe, what is the limiting reactant?
How much Fe3O4 (in grams) will be produced?

9. __MgCl2 + __LiBr  ?????
I have 5.7 grams of LiBr and 2.4 grams of MgCl2. Which is the limiting reactant?
What mass of MgBr2 will be produced?