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# How to Balance a Chemical Equation

A foundational skill in the field of chemistry, balancing chemical equations is essential to understanding chemical reactions. The atoms and molecules of chemicals often recombine into other molecules. Chemical equations show this recombination using the symbols of various periodic elements and their numerical amounts.

For example, the burning of propane to create water and carbon dioxide can be depicted as: C3H8 + O2 H2O + CO2. Representing a transformative chemical change, the arrow symbol in this chemical equation acts very much like the equal sign (=) in the traditional mathematical equation.

Because matter cannot be created or destroyed, chemical equations must contain the same number of atoms on each side. You can use different techniques to balance a simple chemical equation, but a traditional balancing process takes just a few steps.

## 1. Record the number of atoms for each element

Elements without a subscript exist as a single atom. Otherwise, the subscript indicates the number of atoms for that element. Using the provided chemical equation as your guide, record the number of atoms for each element. First, do this for the left (pre-change) side of the equation. Then, do it for the right (post-change) side of the equation. To balance the equation C3H8 + O2 H2O + CO2, you should list C=3, H=8, and O=2 for the left side and C=3, H=2, and O=7 for the right side. It may be helpful to list this information in two vertical columns so that each element sits beside its counterpart on the other side of the equation.

## 2. Save the most common elements for last

With your two coordinated columns in place, you are ready to add coefficients to balance your equation. However, you should approach this process strategically. For easier balancing, you will want to save extremely common elements, such as hydrogen and oxygen, for last. Because hydrogen and oxygen are present in so many molecules, you are quite likely to encounter them on both sides of your equation.