A chemical equation represents a chemical reaction, showing the reactants on the left and products on the right separated by an arrow. For the equation to be balanced, the number of atoms of each type must be equal on both sides. To balance an equation, you take an atom inventory, split the equation into reactants and products, then add coefficients in front of the chemical formulas to make the number of atoms equal on both sides.

1. Balancing Chemical Equations

2. What is a Chemical Equation? When a chemical reaction occurs, it can be described by an equation . This shows the chemicals that react (called the reactants ) on the left-hand side , and the chemicals that they produce (called the products ) on the right-hand side . The chemicals can be represented by their names or by their chemical symbols . Unlike mathematical equations, the two sides are separated by an arrow , that indicates that the reactants form the products

3. The Concept of Balancing Equations Take a look at this chemical word equation: Aluminum + Oxygen Aluminum Oxide This is the equation for the burning of aluminum in oxygen. If we convert each of the chemical names into the appropriate symbols, we get the following: Al + O 2 Al 2 O 3

4. The Concept of Balancing Equations Al + O 2 Al 2 O 3 You can see by looking at it that there is something wrong with this equation. If you count the number of atoms of each type on each side, you will see that there is only one aluminum atom on the left side whereas there are two on the right. There are two oxygen atoms on the left side, as compared to three on the right side. This clearly doesn't match. Left side: Right side:

5. The Rules of Balancing Equations Split the equation into a reactants side and a products side by drawing a line down the center of the arrow Al + O 2 Al 2 O 3 Reactant side Product side

6. The Rules of Balancing Equations Take an atom inventory on each side of the equation – make sure to count the TOTAL number of atoms! Al + O 2 Al 2 O 3 Al 1 O 2 Al 2 O 3

7. The Rules of Balancing Equations Balance the atoms on each side of the equation using COEFFICIENTS __Al + __O 2 __Al 2 O 3 Al O Al O 4 3 2 1 4 2 6 2 4 3 6