1. Balancing Equations

2. When writing a chemical equation, the law of the conservation of mass must be observed
in a chemical reaction, the mass of the products equals the mass of the reactants.
The # of atoms in the reactants = the # of atoms in the products

3. Coefficient – the whole number out front of the formula- tells you how many of each molecule
Subscript – small number to the bottom right of an element- tells you how many atoms of that element are in the molecule.
Ex. 2H2(g) + O2  2H2O

4. Combustion of Methane
Methane gas burns to produce carbon dioxide gas and liquid water
Whenever something burns it combines with O2
Write the equation above:

5. Steps for Writing Equations
Use proper formulas for each reactant and product
Proper equations should be balanced
Count the number of atoms of each element on the reactants side
Count the number of atoms of each element on the products side
Balance atoms by using coefficients
-- Check your work by counting atoms of each element.

6. Balance by Inspection
Polyatomic ions may be counted as one “element” if it does not change in the reaction
Al + FeSO4  Al2(SO4)3 + Fe
If an element appears in more than one compound on the same side, count each separately and add
CO + O2  CO2

7. Pick an element to balance
Use a table if necessary to keep track of your elements
Continue to adjust coefficients until balanced. C O C O # # # #