CHEMICAL EQUATIONS

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CHEMICAL EQUATIONS
Mr. Snyder Science
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Weve all heard that water is

• H2O

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...So what is the Hand what is the O?
H2O

• And whats the deal with the little 2?

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So you have 2 hydrogens and 1 oxygen in a water
molecule.
Oxygen
Hydrogen
H2O
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What if we had 6H2O ?

• How many hydrogen atoms?
• 12
• How many oxygen atoms?
• 6

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In a water molecule2 hydrogens are bonded to 1
oxygen, but how did this happen?
H2
H2O
O2
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Hydrogen burns with oxygen and produces
water. ONLY WATER!!!
PRODUCES

So where is the other oxygen?
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Nobody ever said we used ONE H2 and ONE O2 to
produce ONE water!!!
PRODUCES

In order to produce ONLY water we must bond two
more hydrogens to the other oxygen.
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But we cant just create these hydrogensthey
must come from somewhere. Where?
PRODUCES

We need another H2 as a reactant.
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Lets count up what we have.
PRODUCES

O2
PRODUCES
2 H2

2 H2O
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Look at both sides of the reaction. The mass of
both is the same. ITS BALANCED.
PRODUCES

O2
PRODUCES
2 H2

2 H2O
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In summary, in order to balance, you change the
amount of each substance, but not the identity.
2 H2O
coefficient
subscript
...So you balance by changing coefficients - not
subscripts.
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Balancing Tips

• Find the scariest formula in the skeleton
  equation and try to balance those atoms first.
• Never change the formulas. This means you cannot
  change subscripts.
• Change coefficients until you have an equal
  number of atoms in the reactants and products.
• You may even change your own coefficients as you
  progress.

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Write each skeleton equation, but leave some room
between each one. Balance them.

1. Mg O2 ? MgO
2. Na Cl2 ? NaCl
3. H2O2 ? H2O O2
4. Al O2 ? Al2O3
5. CH4 O2 ? CO2 H20
6. CO2 H2O ? O2 C6H12O6
7. C4H10 O2 ? CO2 H20
8. Combustion of paraffin wax (C30H62)

Try this great web page for more help.
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Here are the answers.

1. 2Mg O2 ? 2MgO
2. 2Na Cl2 ? 2NaCl
3. 2H2O2 ? 2H2O O2
4. 4Al 3O2 ? 2Al2O3
5. CH4 2O2 ? CO2 2H20
6. 6CO2 6H2O ? 6O2 C6H12O6
7. 2C4H10 13O2 ? 8CO2 10H20
8. Help class for the paraffin.