A **chemical equation** is an equation to show how atoms or molecules rearrange during any reaction. In order for a chemical equation to be correct, it must be balanced. It is much like an algebraic equation dealing with variables. Instead of Variables, it is molecules and atoms.

## Balanced Chemical Equation[]

In a basic chemical equation, you multiply what is needed, and then add up the atoms on both sides to see if all atoms are accounted for. If they are, then the Law of Conservation of Matter has been proven . If it has, then the equation is true. an example is the equation to the decomposition of water:

- 2(H
_{2}O) → 2(H_{2})+O_{2}- In H
_{2}O, there are 2 hydrogen atoms. Multiply that by two because of the molecule number, or the 2 on the left of H_{2}O. - There are now 4 Hydrogen atoms and 2 Oxygen atoms on the reactants' side.
- the arrow represents either the reaction, or a catalyst that causes a reaction
- Now we multiply 2 times the H
_{2}molecule, which gives us four atoms. - Finally, we add the O
_{2}, and since there is no number next to it (regularly scripted), we just have 2 Oxygen atoms. - We have 4 hydrogen atoms and 2 oxygen atoms on the products' side.

- In H
**4 hydrogen atoms + 2 oxygen atoms = 4 hydrogen atoms + 2 oxygen atoms**

Now on both sides, we have 4 hydrogen atoms and 2 oxygen atoms. This is balanced. On the other hand, an equation could be written incorrectly, and therefore be false. Example:

- 2(H
_{2}O) → 2(H_{2})+2O_{2}- In H
_{2}O, there are 2 hydrogen atoms. Multiply that by two because of the molecule number, or the 2 on the left of H_{2}O. - There are now 4 Hydrogen atoms and 2 oxygen atoms on the reactants' side.
- the arrow represents either the reaction, or a catalyst that causes a reaction
- Now we multiply 2 times the H
_{2}molecule, which gives us four atoms. - Finally, we multiply 2 times the O
_{2}molecule, which gives us four atoms. - We have 4 hydrogen atoms and 4 oxygen atoms on the products' side.

- In H
**4 hydrogen atoms + 2 oxygen atoms ≠ 4 hydrogen atoms + 4 oxygen atoms**

The error was adding a 2 next to the oxygen molecule where it wasn't needed. That is how you set up, and solve a chemical equation.

## Ionic Equation[]

Chemical Equations are not just limited to adding up and accounting for atoms. There are also *ionic equations*. Ionic equations are chemical equations that involve/include electrolytes as well as atoms/molecules. This includes acid/base reactions, or some reactions where they are simply there, but not being a reactant, product, or catalyst. They are referred to as spectator ions.

## More info on the topic[]

For another explanation on this subject, including a more thorough explanation on Ionic Equations, visit en.wikipedia.org/wiki/Chemical_equation^{[1]}.