INDIVIDUAL BRAINSTORM: Silently, make a list of the best places to get a burger. (1 minute)

GROUP BRAINSTORM: Rank the top three places to get a burger. What made the burger so great? (2 minutes)

A burger “recipe” might look like this:1 Bu + 2 Hb + 1 Ch + 4 Ba 1 Ub

As a group, develop your ultimate burger recipe and write it as an equation. Here are the available ingredients:

Using the ingredients handout from Ms. Brown, answer these questions:1. How many complete burgers can you

make?2. Which ingredient(s) is/are completely used

up?3. How much of each leftover ingredient

remains unused?4. List and explain the steps that your group

used to answer the questions above.

Now, write three (3) problems and their solutions based on your burger recipe.

Example: If Annie has 18 strips of bacon, how many burger patties does she need to completely use up her bacon?

1 Bu + 2 Hb + 1 Ch + 4 Ba 1 Ub

18 Ba 2 Hb = 9.0 Hb4 Ba

Your ultimate burger recipe Your answers to the 4 questions Your three problems with solutions Your group answers to these

reflection questions:1. How well did your group come to

consensus today? Explain.2. What do you think that this activity has to

do with chemistry content?3. Are you hungry right now?

[stoy-key-AH-meh-tree]

DEFINITION: calculation of quantities in reactions

KEY STEP: mole ratio from balanced equation

So, to do stoichiometry, you need a balanced equation!

N2 + 3 H2 2 NH3

1 molecule N2 + 3 molecules H2

2 molecules NH3

1 mole N2 + 3 moles H2 2 moles NH3

28.02 g N2 +3(2.016) g H2 =

6.048 g H2

2(17.0343) g NH3 = 34.068 g

NH3

particle

smole

smas

s

4 Fe + 3 O2 2 Fe2O3

+

+

+

particle

smole

smas

s

Ratio between the numbers of moles of any two substances in a balanced chemical equation

Example: 2 KClO3 2 KCl + 3 O2

How many moles of oxygen gas can be produced by the reaction of 5.85 moles of potassium chlorate?

2 KClO3 2 KCl + 3 O2

How many liters of oxygen gas at STP can be produced by the reaction of 47.9 grams of potassium chlorate?

2 KClO3 2 KCl + 3 O2

rep. particles A

rep. particles B

grams A mole Ause mole ratio!

mole B grams B

liters A liters B

How many liters of oxygen gas at STP can be produced by the reaction of 47.9 grams of potassium chlorate?

2 KClO3 2 KCl + 3 O2