Balancing Chemical Equations

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Balancing Chemical Equations
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Rules

• 1. LEARN THESE DIATOMIC MOLECULES
• O2 H2 N2 F2 Cl2 Br2 I2
• 2. The same number of atoms of each element
  appearing in reactants must appear in the
  products.
• 3. The subscripts of a formula cannot be changed
  to balance the equation. Each compound must
  retain its stableness via oxidation states.
• 4. Choose compound with greatest number of atoms
  first.
• 5. Balance by placing necessary coefficients in
  front of entire molecules. NO SUBSCRIPT
  CHANGES!

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Rules cont.

• 6. Be certain each side of equation has same
  number of atoms of each type.
• 7. Make sure coefficients are in lowest whole
  number ratios.
• 8. Polyatomic ions usually stay intact, but
  multiple polyatomic ions may be separated.
• 9. (aq.) stands for aqueous which is Latin for
  water solution
• (g) gas (l) liquid (s) solid
  (c) crystalline solid

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More Rules

• ? means yields and shows direction of action
• ? above arrow shows heat has been added
• ?? shows reaction is reversible
• MINOH try Metals first, then Ions, then
  Nonmetals, and Oxygen, then Hydrogen last

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Sample Problem

• C8H18 O2 ? CO2 H2O
• C8H18 O2 ? __ CO2 __ H2O
• C8H18 __ O2 ? __ CO2 __ H2O
• __ C8H18 __ O2 ? __ CO2 __ H2O

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Practice Problems

• H2CrO4 AgNO3 ? Ag2CrO4 HNO3
• (aq) (aq)
  (s) (aq)
• Chromic Silver ? Silver Nitric
• Acid Nitrate Chromate
  Acid
• 1, 2, 1, 2 Double displacement

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Problem 6

• Cu(NO3)2 ? CuO NO2 O2
• (aq) (s)
  (g) (g)
• Copper (II) ? Copper (II) Nitrogen Oxygen
• Nitrate Oxide
  Dioxide Gas
• 2, 2, 4, 1 Decomposition

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Problem 14

• AlBr3 Cl2 ? AlCl3 Br2
• (aq) (g) (aq)
  (g)
• Aluminum Chlorine ? Aluminum Bromine
• Bromide Gas Chloride
  Gas
• 2, 3, 2, 3 Single Displacement

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Problem 2

• P4 O2 H2O ? H3PO4
• (s) (g) (aq) (aq)
• Phosphorus Oxygen Water ? Phosphoric
• (free) gas
  acid
• 1, 5, 6, 4 Synthesis

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Problem 20

• sodium permanganate sulfuric acid ? sodium
  sulfate manganese (VII) oxide water
• NaMnO4 H2SO4 ? Na2SO4 Mn2O7 H2O
• (aq) (aq) (aq)
  (s) (l)
• 2, 1, 1, 1, 1 Double Displacement

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Problem 3

• Th(NO3)4 K3PO4 ? Th3(PO4)4 KNO3
  
• (aq) (aq)
  (s) (aq)
• Thorium Potassium ? Thorium Potassium
• Nitrate Phosphate Phosphate
  Nitrate
• 3, 4, 1, 12 Double Displacement

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Problem 22

• sulfur trioxide nitric acid ? sulfuric acid
  nitrogen (V) oxide
• SO3 HNO3 ? H2SO4 N2O5
• (g) (aq) (aq)
  (g)
• 1, 2, 1, 1 Double Displacement

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Problem 7

• NH4NO3 Ca(OH)2 ? Ca(NO3)2 NH3 H2O
• (aq) (aq)
  (aq) (g) (l)
• Ammonium Calcium ? Calcium Ammonia water
• Nitrate Hydroxide Nitrate
• 2, 1, 1, 2, 2 Double
  Displacement

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Missing Products

• sodium chloride potassium iodide ?
• NaCl KI ? ________ _________
• (aq) (aq) (?)
  (?)
• Does a reaction take place?

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Balancing Wars Problem 1

• CuSO4 H3PO4 ? _____ ______
• (aq) (aq)
• 3, 1, 2, 1
• 3, 1, 1, 3
• 2, 3, 3, 2
• 3, 2, 1, 3
• 2, 3, 3, 1
• ((D))
• Copper (II) Phosphoric ? Copper (II)
  Sulfuric
• Sulfate Acid
  Phosphate Acid

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Balancing Wars Problem 2

• Mg(OH)2 H3PO4 ? _____ ______
• (aq) (aq)
• 1, 1, 1, 1
• 3, 2, 1, 3
• 2, 3, 1, 6
• 2, 3, 1, 1
• 3, 2, 1, 6
• ((E.))
• Magnesium Phosphoric ? Magnesium Water
• Hydroxide Acid
  Phosphate

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Balancing Wars Problem 3

• CuCl2 Na3PO4 ? _____ ______
• (aq) (aq)
• 1, 2, 1, 2
• 2, 3, 1, 6
• 2, 3, 1, 1
• 3, 2, 1, 6
• 1, 1, 1, 1
• ((D))
• Copper (II) Sodium ? Copper (II)
  Sodium
• Chloride Phosphate Phosphate
  Chloride

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Balancing Wars Problem 4

• Potassium Nickel (II) ? _____
  ______
• Permanganate Nitrate
• 2, 1, 2, 1
• 2, 1, 3, 1
• 1, 2, 1, 2
• 1, 2, 1, 3
• 1, 1, 1, 1
• ((A))
• KMnO4 Ni(NO3)2 ? KNO3 Ni(MnO4)2

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Balancing Wars Bonus Problem

• KMnO4 Na2C2O4 H2SO4 ?
• K2SO4 Na2SO4 MnSO4 CO2 H2O