Chemical Equations

Chemical equations are widely used in chemistry textbooks and are often tested in chemistry exams. Knowing chemical equations is key and understanding how to balance chemical equations is critical in passing a chemistry examination. Writing chemical equations out helps with predicting chemical products in a chemical reaction. If you are struggling with balancing chemical equations, see balancing chemical equations worksheet for practice in writing and balancing chemical equations.

What is a chemical equation?

A chemical equation is a useful summary of a chemical reaction. It is possible to obtain the chemical equation from the results of a chemical experiment. When answering a chemistry question, you should always write down the chemical equations if possible even if you are not asked to do so. Mathematicians communicate using math symbols and formulas, chemists communicate with chemical equations.

Writing chemical equations

Below are steps of how to write chemical equations.

1. write down the chemical equation as a word equation (without chemical symbols) using the information given in the problem or experiment. If you know the chemical reaction well, you can also write it down from memory. When writing chemical equations, include all reacting substances or reactants and all products. Do not forget small molecules such as water. For example:
2. Fill in the correct formulas for all the reacting substances AND products. From the above reaction, the chemical equation becomes:
3. The last step of writing chemical equations is to balance the chemical equation. The rule for balancing chemical reactions is that during a chemical reaction, atoms cannot be created or destroyed. This is the Law of Conservation of Mass. There must be the same total numbers of the different atoms before and after the chemical reaction. Tip for balancing chemical equations: when balancing chemical equations, only the proportions of the reaction substances and products can be altered, not the chemical formulas. The chemical equation above becomes: