# What-is-Stoichiometry

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```					 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
 Asa group, develop your ultimate burger recipe
and write it as an equation. Here are the
available ingredients:
   Using the ingredients handout from Ms.
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
   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 Hb
4 Ba
 Your three problems with solutions
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

3(2.016) g H2 =   2(17.0343) g NH3
28.02 g N2     +
6.048 g H2       = 34.068 g NH3
4 Fe   +   3 O2   2 Fe2O3
+

+

+
   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 A                     mole B   grams B
use mole ratio!

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

```
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 views: 3 posted: 2/26/2012 language: pages: 16