1. Intro to Stoichiometry
January 28, 2019

2. Cookies!!!
What is required to make chocolate chip cookies (according to the Nestle Toll House recipe)?

3. Ingredients Sugar Chocolate Chips Br. Sugar Vanilla Eggs Butter Flour
Baking soda
Salt

4. Ratios Matter!!!! 0.75 cp Sugar 1 tsp Salt 0.75 cp Br. Sugar
16 oz Chocolate Chips
2 Eggs
1 tsp Vanilla
2.25 cp Flour
1 cp Butter
1 tsp Baking soda

5. As an equation 0.75 cp Sugar + 0.75 cp Br. Sugar +
2 Eggs cp Flour +
1 tsp Baking soda + 1 tsp Salt +
16 oz Chocolate Chips + 1 tsp Vanilla +
1 cp Butter → 60 cookies

6. Application 6 eggs 60 cookies x = 180 cookies 2 eggs
0.75 cp Sugar cp Br. Sugar + 2 Eggs cp Flour +
1 tsp Baking soda + 1 tsp Salt + 16 oz Chocolate Chips +
1 tsp Vanilla + 1 cp Butter → 60 cookies
So how many cookies could you make if you had unlimited ingredients but only 6 eggs? Use dimensional analysis!
6 eggs
60 cookies x =
180 cookies
2 eggs

7. Application 6 eggs 0.75 cp sugar x = 2.25 cp sugar 2 eggs
0.75 cp Sugar cp Br. Sugar + 2 Eggs cp Flour +
1 tsp Baking soda + 1 tsp Salt + 16 oz Chocolate Chips +
1 tsp Vanilla + 1 cp Butter → 60 cookies
So how much sugar would you use to bake with 6 eggs? Use dimensional analysis!
6 eggs
0.75 cp sugar x =
2.25 cp sugar
2 eggs

8. So in chemistry: Let’s look at a chemical equation:
CaCO3(s) + HCl (aq) →

9. So in chemistry: Let’s look at a chemical equation:
CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2CO3(aq)

10. Important note:
H2CO3 is called carbonic acid and is quite unstable. When you see it as a product, you need to break it apart into H2O + CO2!

11. So in chemistry: Let’s look at a chemical equation:
CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2CO3(aq)
CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2O(l) + CO2(g)

12. What does this equation mean?
CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2O(l) + CO2(g)
1 mol CaCO3 reacts with
2 mol of HCl to produce
1 mol of CaCl2 and
1 mol of H2O and
1 mol of CO2

13. Mole Ratios!!!!
The balanced equation gives you mole ratios, not mass (gram) ratios!!!

14. Answer with unit, substance, and rounded correctly
Let’s practice
CaCO3(s) + 2HCl (aq) → CaCl2(aq) + H2O(l) + CO2(g)
How many moles of CO2 can be produced when 4.5 moles of HCl react in the reaction above?
4.5 mol HCl
1 mol CO2 x =
2.3 mol CO2
2 mol HCl
Answer with unit, substance, and rounded correctly
Start with given
Use conv factor

15. New reaction
Predict the products of hydrogen monofluroide reacting with aluminum carbonate. Write the balanced equation.
6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2CO3
6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2O + 3 CO2

16. Stoichiometry Practice
How many moles of HF are required to react with 8.29 mol of Al2(CO3)3?
6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2O + 3 CO2
8.29 mol Al2(CO3)3
6 mol HF x =
49.7 mol HF
1 mol Al2(CO3)3
Answer with unit, substance, and rounded correctly
Start with given
Use conv factor

17. Stoichiometry Practice
How many moles of AlF3 can be produced when 33.5 moles of H2O are produced in the following reaction?
6 HF + Al2(CO3)3 → 2 AlF3 + 3 H2O + 3 CO2
2 mol AlF3
33.5 mol H2O x =
22.3 mol AlF3
3 mol H2O
Answer with unit, substance, and rounded correctly
Start with given
Use conv factor

18. Last practice problem
If 18.9 g of H2 reacts with excess O2, what mass of water will be produced?
2 H2 + O2  2 H2O
1 mol H2
18.9 g H2
2 mol H2O
18.02 g H2O x x x =
2.02 g H2
2 mol H2
1 mol H2O
169 g H2O

19. Time for Homework!