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To see how chemical equations work, you will look at five equations that deal with everyday reactions.

Ice melting

solid water + heat → liquid water

Notice that a chemical reaction can involve something as simple as changing the state of an object. In this case, ice has changed into water.

An engine providing power

gasoline + oxygen → heat + energy + carbon dioxide + water vapour

In any engine, a form of fuel such as gasoline combines with oxygen to produce the required power and other products.

Relieving an upset stomach

sodium bicarbonate + hydrochloric acid → sodium chloride + water + carbon dioxide gas

This is the word equation for what occurs in your stomach when you have an upset stomach and take an antacid such as Tums or Gaviscon brand products. Sodium bicarbonate reacts with the hydrochloric acid in your stomach to produce sodium chloride (salt), water, and carbon dioxide gas. The fact that carbon dioxide gas is produced is why some people burp a lot after taking antacids.

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Cellular respiration

food + oxygen → carbon dioxide + water + energy

This chemical reaction occurs in the cells of your body. This is how your body gets its energy for you to grow, to repair injuries, and to live.

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Photosynthesis

carbon dioxide + water + light energy → sugar + oxygen

Photosynthesis occurs in green plants. The plant takes in carbon dioxide and water in the presence of sunlight and produces sugar or energy for the plant to live and oxygen for us to breathe.

As you can see, chemical reactions can be very simple or they can be very complex. In each of these equations, the reactants are joined with a plus (+) sign. Between the reactants and the products is an arrow (→) that represents the word "produces." The products are joined by a plus (+) sign as well.

Click on the Play button to watch a video that further explains how to write word equations for chemical reactions.