#### What is a Chemical Equation

Chemical Equations, like the one on the right are how you can write out a reaction. Everything on the left side of the arrow is called a reactant and everything on the right side of the arrow is called a product.

#### What do the numbers mean?

The large numbers (shown in blue in this example) show how many of each molecule is needed to complete the reaction. The small numbers, shown in red show how much of each element is needed to create the molecules in the products and reactants.

#### What is balancing chemical equations?

A chemical equation is balanced if the number of each element is the same in the products as the reactants. This example is balanced because there are 4 hydrogen, 2 oxygen, and 1 carbon on each side. Often, a question won't tell you how many of each molecule is in the equation (the numbers in blue are missing). Balancing equations involves figuring out how many of each molecule is needed so that each side has the same number of each element.

#### Net Ionic Equations

Net ionic equations simplify chemical equations by removing "spectator ions." Spectator ions are reactants that do not change form on the products side of the reaction. Identify spectator ions by looking at whether the reactants and products are aqueous, solid, liquid or gas. If two aqueous solutions are mixed, the precipitate or gas product will remain in the net ionic equation, and the ions that remain aqueous will be removed as spectator ions because they did not change form.

Example:

1. Write out chemical equation and states: NaOH (aq) + HCl (aq) --> NaCl (aq) + H2O (l)

2. Separate into ions: Na(+)(aq) + OH(-)(aq)+H(+)(aq)+Cl(-)(aq) --> Na(+)(aq)+Cl(-)(aq)+H2O(l)

3. Cancel out what matches on each side (the spectator ions): H(+)+OH(-)-->H2O

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