Reaction Stoichiometry

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Reaction Stoichiometry

• Weight relations in chemical reactions
• If I react this much, how much product do I get?
• If I need this much product, how much do I need
  to react

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1. If you have 200 tires, how many cars can you
make? 1. 200 2. 100 3. 800 4.
50    2. If you have 200 tires, how many
motorcycles can you make? 1. 200 2. 100 3.
800 4. 50 
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• 3. Consider
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• Pb(NO3)2(aq) 2 NaCl(aq) --gt PbCl2(s) 2
  NaNO3(aq)
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• If you have 5 moles of Pb(NO3)2, how many moles
  of PbCl2 can you make?
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• 1. 5 2. 10 3. 2.5
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• 4. Consider
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• Pb(NO3)2(aq) 2 NaCl(aq) --gt PbCl2(s) 2
  NaNO3(aq)
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• If you have 5 moles of NaCl, how many moles of
  PbCl2 can you make?
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• 1. 5 2. 10 3. 2.5

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How to Balance Equations

• One element at a time
• Trial and error

Al Br2 Al2Br6
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CH3CH2OH O2 CO2
H2O
CH3OH O2 CO2
H2O
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General Stoichiometry Route
Grams reactant
Moles reactant
Moles product
Grams product
amounts table
2 CH3OH 3 O2 2 CO2 4
H2O
If we react 100 grams of CH3OH, how many grams of
H2O are formed?
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Limiting Reactants 1. If you have 200 tires and
75 steering wheels, how many cars can you
make? 1. 200 2. 75 3. 50 4. 100
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Example 2.

• A cake recipe calls for 3 eggs, 2 cups of flour,
  and 3 teaspoons of sugar. If you have
• 9 eggs
• 8 cups of flour
• 12 teaspoons of sugar
• how many cakes can you make?
• Enter the number of cakes.

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Example 3. Which reaction is correct?
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A hard OWL Question
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Alum Lab Calculations Lets say you start with
0.985 g Al and make 14.8 g KAl(SO4)2?12 H2O
product. What is the percent yield?
Molar masses Al 26.98 KAl(SO4)2?12 H2O
474.37 g/mol
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Chemical Analysis
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Chemical Analysis Determining Formulas