Stoichiometric Calculations

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Stoichiometric Calculations

• Foldable

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Foldable

• Obtain 3 sheets of paper.
• Stagger the pages about ¾ of an inch.
• Fold over so you have multiple flaps.

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Titles of Pages
Stoichiometric Calculations
Mole to Mole
Mole to Mass / Mass to Mole
Mass to Mass
Limiting Reactant
Percent Yield
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Page 1 - Top

• Open your book, on the top flap, write the
  following
• Steps in all stoichiometric calculations
• Write a balanced equation
• Identify the known and unknown, what do you have
  and what are you trying to find?
• Set up the problem with the given information
• Identify the mole ratio
• Check your answer, does it make sense?

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Page 1 Bottom Mole to Mole

• Mole of A to Mole of B
• Ex. How many moles of H2O are produced from 5.0
  moles of H2?
• Balanced Eq 2H2 O2 ? 2H2O
• Known 5.0 mol H2, Unknown mols of H2O
• 5.00 mol H2O

5.0 mol H2
2 mol H2O
2 mol H2
Mole Ratio
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Page 2- Bottom Mass to Mole

• Mole of A to Mass of B

• Mass of A to Mole of B

• How many grams of NaCl are produced from 5 moles
  of Na?
• Balanced Eq 2 Na Cl2 ? 2 NaCl
• Known 5 moles of Na
• Unknown grams of NaCl
• 
  

• How many moles of NaCl are produced from 35 g of
  Cl2?
• Balanced Eq 2 Na Cl2 ? 2 NaCl
• Known 35 g Cl2
• Unknown moles NaCl

5 mol Na
58.44 g NaCl
2 mol NaCl
35 g Cl2
1 mole Cl2
2 mol NaCl
2 mol Na
70.90 g Cl2
1 mole Cl2
1 mol NaCl
Mole Ratio
0.99 mol NaCl
292.20 g NaCl
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Page 3 Bottom- Mass to Mass

• Mass of A to Mass of B
• Ex. How many grams of NO2 are produced from 250 g
  of N2 gas?
• Balanced Eq N2 2O2 ? 2NO2
• Known 250 g of N2
• Unknown grams of NO2
• 
  
• 821.02 g NO2

46.01 g NO2
1 mol N2
2 mol NO2
250 g N2
28.02 g N2
1 mol N2
1 mol NO2
Molar Mass
Mole Ratio
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Page 4 Bottom Limiting ReactantsSame as all
the other problems, you just have to do two of
them.
If you have 25 g of N2 and 35 g of O2, how many
grams of NO2 is produced, which one is the
limiting reactant? The excess reactant?

• Do the problem with N2 first.
• Balanced Eq N2 2O2 ? 2NO2
• Known 25 g N2, Unknown g NO2
• 82.10 g NO2

• Now do the same problem with O2
• Same balanced equation
• Known 35 g O2 ,Unknown g of NO2
• 
  
• 50.32 g NO2

46.01 NO2
25 g N2
1 mol N2
2 mol NO2
46.01 g NO2
35 g O2
1 mol O2
2 mol NO2
28.02 g N2
1 mol N2
1 mol NO2
32.00 g O2
2 mol O2
1 mol NO2
50.32 g NO2 is produced
NO2 is the excess reactant, it will be left over
after the reaction.
O2 is the limiting reactant, this reactant will
determine how much product is made.
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Page 5 Bottom - Yield

• Ex. Problem When this experiment was performed
  in the lab, the chemist was able to produce 48.45
  g of NO2.
• 48.45 g NO2 actual yield
• Yield actual yield

• Done the same way if you need to figure out the
  amount of product use the limiting reactant
  steps.
• We will use the same balanced equation N2 2O2
  ? 2NO2
• We know that 50.32 g NO2 is produced.
• The amount of product you calculate from the
  limiting reactant problem is the theoretical
  yield.
• 50.32 g NO2 theoretical yield
• 
  

X 100
theoretical yield
Yield 48.45
X 100
50.32
96.3