1. Ch 7.1 Stoichiometry Assignment: Hebden, p. 124 #1-4 all

2. Party Up!

3. It’s your birthday. You are going to make 6 burgers for your guests whom you have invited to your party. Here’s the recipe to make your delicious BLT (Bacon Lettuce Tomato) Burger.

4. IngredientsSymbolsCoefficient (Smallest Ratio) MultipleRequired Amount 2 slices of tomatoT2612 1 wedge of lettuceL16 3 strips of baconB318 1 burger pattyP16 1 bunBu16 Q1: To make 6 burgers, how much of each ingredient do you need? Tomato: ___2__slices; Lettuce: __1_ wedges;Bacon: _3___ strips; Burger Patty: ___1__ Buns: _1____ Q2: Did you know that you have just used stoichiometry? Let’s translate this into chemistry language. “The Burger Reaction” 2T +1L +3 B +1P +1Bu= 1 BLT__

5. Stoichiometry Q3: What do the coefficients in a balanced equation represent? The coefficients in a balanced equation represent the _number__ which describe the __ mole ratio_ relationship of the reactants and products. They represent:  The number of __MOLES_of reactants___.  The number of __MOLES of products__  We call this the __ Stoichiometry. Therefore, to make 6 burgers, you can multiply each coefficient by 6 to get: 12_ Tomato, _6_ Lettuce, 18 Bacon, 6 Patty, _6 Bun  6 BLT

6. Background: What is Stoichiometry?  Definition: Stoichiometry is the relationship between the amount of _reactants__ in a chemical reaction and the amount of __products___ in a chemical reaction. The Greek root “stoicheion” means “element”; the suffix “-metry” means “to measure”. Why do we study stoichiometry?  The mole ratio can be used to predict the amount of reactant and product in a chemical reaction.

7. I) Mole: Mole Problems Step 1: Start with the given. Step 2: Use the mole ratio as a “conversion factor”.  The mole ratio relates the 2 species of interest.  Include the name of the species in your equation, otherwise you’ll get confused! Note: Same species (chemicals) in the nominator & denominator cancel.

8. 1.Consider the combustion of propane: C 3 H 8(g) + 5 O 2(g)  3 CO 2(g) + 4 H 2 O (l) Given: Balanced chemical reaction C 3 H 8(g) + 5 O 2(g)  3 CO 2(g) + 4 H 2 O (l) Mole ratio: C 3 H 8(g) : 5 O 2(g)  3 CO 2(g) : 4 H 2 O (l) =1:5:3:4 Examples:

9. a) How many molecules of C 3 H 8 are required to react with 10 molecules of O 2 ?

11. b)How many moles of CO 2 are produced when 2 mole of C 3 H 8 are reacted?

12. Mole ratio:C 3 H 8(g) : 3 CO 2(g = 1: 3 = 2:6 Therefore, 2 moles of propane will produce 6 moles of CO2 Answer: 2 moles of propane will produce 6 moles of CO2

13. 2. Consider the reaction: 4 NH 3(g) + 5 O 2(g)  6 H 2 O (g) + 4 NO (g) Given: Balanced chemical reaction: 4 NH 3(g) + 5 O 2(g)  6 H 2 O (g) + 4 NO (g) Mole ratio:

14. 2. Consider the reaction: 4 NH 3(g) + 5 O 2(g)  6 H 2 O (g) + 4 NO (g) Given: Balanced chemical reaction: 4 NH 3(g) + 5 O 2(g)  6 H 2 O (g) + 4 NO (g) Mole ratio: 4 NH 3(g) : 5 O 2(g) : 6 H 2 O (g) : 4 NO (g) = = 4 : 5 : 6 : 4

15. a)How many molecules of NH 3 are required to react with 15 molecules of oxygen? Mole ratio: 4 NH 3(g) :5 O 2(g) : 6 H 2 O (g) : 4 NO (g) = 4 : 5 : 6 : 4

16. a)How many molecules of NH 3 are required to react with 15 molecules of oxygen? Mole ratio: 4 NH 3(g) :5 O 2(g) : 6 H 2 O (g) : 4 NO (g) = 4 : 5 : 6 : 4 Therefore, 12 molecules of Ammonia will react with 15 molecules of O2, mole ratio 12:15 =4:5 Answer: 12 molecules of Ammonia will react with 15 molecules of O2

17. b)How many moles of NO are produced when 16 mole of NH 3 are reacted? Mole ratio: 4 NH 3(g) : 5 O 2(g) : 6 H 2 O (g) : 4 NO (g) = 4 : 5 : 6 : 4

19. 3. A student decomposes some hydrogen peroxide, H 2 O 2, according to the equation: 2H 2 O 2  2H 2 O + O 2 If a total of 0.125 mol of reactants and products are involved in the reaction, how many moles of O 2 are produced? Given: Balanced chemical reaction 2H 2 O 2  2H 2 O + O 2 Mole ratio:

20. 3. A student decomposes some hydrogen peroxide, H 2 O 2, according to the equation: 2H 2 O 2  2H 2 O + O 2 If a total of 0.125 mol of reactants and products are involved in the reaction, how many moles of O 2 are produced? Given: Balanced chemical reaction 2H 2 O 2  2H 2 O + O 2 Mole ratio: 2 H 2 O 2 : 2 H 2 O : O 2 = 2 : 2 : 1 = 40% : 40% : 20% Total amount is 0.125 mol = 100% # mole of O2 (20 % of total) = = (0.125 mol x 20 %) : 100 % = 0.0250 mol Answer: 0.025 mol of oxygen is produced

22. Suddenly, your training manager comes around for a skill test question to your dismay. “How many burgers can you make if you were given 22 slices of tomato, 14 wedges of lettuce, 18 strips of bacon, 35 burger patties and 26 buns?” If you want to pass this trial period and keep your holiday part-time job, you need to study stoichiometry!!! What is the answer? Your New Job at MacDonald’s: You have just gotten your seasonal job at McDonald’s and you are really excited to start making some money. Your position is working with the grill. Your first challenge is to make as many burgers as you can as it gets very busy during the Christmas season

23. Q: What’s the chemical equation for the burger reaction? Q: How much of each ingredient did you start with? Q: What is the mole ratio?

24. Q: What’s the chemical equation for the burger reaction? 2T + L + 3Ba + P + Bu  BLT Q: How much of each ingredient did you start with? Tomato: 22, Lettuce: 14, Bacon: 18, Patty: 35, Bun: 26 Q: What is the mole ratio? 2: 1: 3: 1: 1  1

25. Q: From the ratios, what are the amounts of ingredients “reacted” (consumed)? Q: What are the amounts of ingredients left over (unreacted)? Q: How many burgers were made?

26. Q: From the ratios, what are the amounts of ingredients “reacted” (consumed)? Tomato: 12, Lettuce: 6, Bacon: 18, Patty: 6, Bun: 6 Q: What are the amounts of ingredients left over (unreacted)? Tomato: 12, Lettuce: 6, Bacon: 18, Patty: 6, Bun: 6 Q: How many burgers were made? 6 burgers! Note: The number of burgers produced is determined by the amount of bacon, which is in the least supply. The reactant in least supply is called the limiting reagent, which we will explore later.

27. CONGRATULATIONS! You have passed your skill test. If you pass the next one, your manager will give you a raise from your minimum hourly pay. Challenge : The ingredients are purchased by mass in the supermarket. How can you convert the mass of ingredients to the number of tomatoes, lettuce, bacon, patty and buns?

28. What did you learn?  How to balance chemical reactions using Stoichiometry  What is the Mole Ratio

29. Homework  Assignment: Hebden, p. 124 #1-4 all