1. Balancing Chemical Equations
Atoms can’t be created or destroyed in an ordinary reaction:
All the atoms we start with we must end up with
A balanced equation has the same number of each element on both sides of the equation.

2. Rules for balancing:
Assemble the correct formulas for all the reactants and products, use + and →
Count the number of atoms of each type appearing on both sides
Balance the elements one at a time by adding coefficients where needed (the numbers in front) - save balancing the H and O until LAST!
4) Check to make sure it is balanced.

3. Never Never change a subscript to balance an equation.
If you change the formula you are describing a different reaction.
H2O is a different compound than H2O2
Never put a coefficient in the middle of a formula
2NaCl is okay, but Na2Cl is not.

4. 2
Mg + O2 2
MgO +

5. 2
Mg + O2 2
MgO +

6. (NH4)2Cr2O Cr2O3 + N H2O
Reactants Products N Cr H O

7. Practice Balancing Examples
_AgNO3 + _Cu ® _Cu(NO3)2 + _Ag
_Mg + _N2 ® _Mg3N2
_P + _O2 ® _P4O10
_Na + _H2O ® _H2 + _NaOH
_CH4 + _O2 ® _CO2 + _H2O

8. Practice Balancing Examples
2AgNO3 + 1Cu ® 1Cu(NO3)2 + 2Ag
3Mg + 1N2 ® 1Mg3N2
4P + 5O2 ® 1P4O10
2Na + 2H2O ® 1H2 + 2NaOH
_CH4 + 2O2 ® _CO2 + 2H2O

9. __Ag2CO3 __Ag2O + __CO + __O2
__NaClO4 + __CuSO4  __Na2SO4 + __ Cu(ClO4)2
__Ga + ___I2  ___Ga I3
__Cr2O3  __ CrO __O2
___Sn + __Ag2 SO4  __ Sn(SO4)2 + __ Ag

10. _1Ag2CO3 1 Ag2O _1_CO ½ O2 OR
_2NaClO4 + _1CuSO4  _1Na2SO4 + _1 Cu(ClO4)2
_2Ga + __3I2  __2Ga I3
_2Cr2O3  _4 CrO _1O2
_1_Sn + _2Ag2 SO4  1 Sn(SO4)2 + _4_ Ag