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Balancing chemical equations

Atoms can neither be destroyed nor created during a simple chemical reaction. Therefore, in a chemical reaction

The sum of atoms before reaction = the sum of atoms after reaction

The following figure gives some hints on how to balance chemical equations. Scroll down the page for more examples and solutions.

Balance Chemical Equations

General Rules for balancing chemical equations

Balancing chemical equations may require some trial and error. There are some general rules that could be helpful, but they may not work all the time.

In this page, we will look at some examples of applying

Rule 2: Balancing chemical equations using the two’s and three’s technique.


Balance the equation

Fe + O2 → Fe2O3


Step 1: On the left side of the equation there are 2 oxygen atoms and on the right side of the equation there are 3 oxygen atoms. To balance the oxygen atoms, multiply Fe2O3 by the coefficient of 2 and the O2 by the coefficient of 3

Fe + 3O2 → 2Fe2O3

Step 2: Balance the Fe by placing the coefficient of 4 in front of Fe

4Fe + 3O2 → 2Fe2O3

Step 3: Check that all the atoms balance and make sure that all coefficients are in the lowest-possible ratio.

Examples of using the two's and three's method to balance chemical equations

Rotate to landscape screen format on a mobile phone or small tablet to use the Mathway widget, a free math problem solver that answers your questions with step-by-step explanations.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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