Tutorial
Law of Conservation of Mass
LoCoM: states that mass cannot be created or destroyed
 The mass of the reactants is equal to the mass of the product
Reactant
Product
The same thing is true for chemical equations; each side has to
have the same mass as the other.
 Keep in mind that you cannot change the individual element in a
compound; you have to change the amount of the entire compound.

Balancing Equations
Goal: to have the same amount of each element in
the compounds on either side of the equation.
Step 1: look at the equation and figure out the
value of each element
Al + CuCl2
1 1 2

AlCl3 + Cu
1 3
1
The numbers (values) under the seesaw should eventually be
equal on both sides after these following steps.
Balancing Equations (cont.)
Step 2: Choose which element you want to
balance first. (This example will use
chlorine [Cl])
Al + 3CuCl2
1 1 2
3 6
 2AlCl3 + Cu
1
2
3
6
1
You have to change the amount of every element
or compound. Since you cannot change the
subscript, you have to change the amount of the
compounds as a whole.
Balancing Equations (cont.)
Step 3: Because you changed each compound as a whole,
other elements were affected. In this case, it was copper
(Cu) and aluminum (Al).
2Al + 3CuCl2  2AlCl3 + 3Cu
1 3
2
6
2
6
1
3
The Al was changed to 2Al and the Cu was
changed to 3Cu because when we changed the
amount of the compounds in step 1, the amount
of the element’s on the opposite sides were
changed.
The Balanced Equation

Step 4: Check to make sure every element has the
same mass as its counterpart on the opposite
side.
2Al + 3CuCl2  2AlCl3 + 3Cu
2
3 6
2 6
3
If you notice on the bottom, there is a
2, 3, and 6 on each side. This is a
good indication that the equation is
equalized.
Bibliography
1)
http://richardbowles.tripod.com/chemistry/
balance.htm (Balancing Chemical Equations)
2)
http://misterguch.brinkster.net/eqnbalance.
html (How Can I Balance A Chemical Equation?)
Picture Website:
http://www.chemistry.ohio-state.edu/betha/nealChemBal/