Balancing Equations

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Balancing Equations

• Ch. 8 Chemical Reactions

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A. Balancing Steps

• 1. Write the unbalanced equation.
• 2. Count atoms on each side.
• 3. Add coefficients to make s equal.
• Coefficient ? subscript of atoms
• 4. Reduce coefficients to lowest possible
  ratio, if necessary.
• 5. Double check atom balance!!!

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B. Helpful Tips

• Balance one element at a time.
• Update ALL atom counts after adding a
  coefficient.
• If an element appears more than once per side,
  balance it last.
• Balance polyatomic ions as single units.
• 1 SO4 instead of 1 S and 4 O

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C. Balancing Example

• Aluminum and copper(II) chloride react to form
  copper and aluminum chloride.

3
3
2
2
1 1 1 1 2
3
2 ?
? 2 ? 6
3 ? 6 ?
? 3
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Balance the following equations
3
3
2

• 1.) Fe2O3 H2 ? Fe H2O

2 1 3 1 2
2
Fe O H
? 2
? 3
6 ?
? 6
6
2
2
2.) AgNO3 H2S ? Ag2S HNO3
Ag NO3 H S
1 2 1 1 2
1 1 1
2 ? 2 ?
? 2
? 2
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Problems (cont.)

• 3.) Zn(OH)2 H3PO4 ? Zn3(PO4)2 H2O

4.) SO2 O2 ? SO3

• 5.) MnO2 HCl ? MnCl2 H2O Cl2