Just as we need oxygen to keep living, some types of reactions need oxygen to occur. Two of these are combustion and corrosion. In this activity, you will learn the difference between combustion and corrosion.

Combustion is a chemical reaction that occurs when oxygen reacts with something to form a new substance and gives off energy. Combustion takes place when fuel, most commonly a fossil fuel, reacts with the oxygen in air to produce heat and light. The heat created by the burning of a fossil fuel is used in the operation of equipment such as boilers, furnaces, kilns, and engines.

A campfire is another great example of a combustion reaction. Wood and oxygen react to give off heat and light and to produce carbon dioxide and water. If oxygen is not available to the wood, the fire will die. This happens when you cover the fire with dirt, and you can leave it safely when the ashes are cold! You are taking away the oxygen source, and the fire dies. The same thing occurs when you use a fire extinguisher that is filled with carbon dioxide. The carbon dioxide replaces the oxygen, and the fire dies.

Corrosion, on the other hand, is the slow chemical change that occurs when oxygen in the air reacts with a metal.

Does your car have some rust spots? One of the most common examples of corrosion is rust, which occurs when iron reacts with oxygen to form iron oxide. Rust on vehicles can be a major problem. One of the best things you can do with your vehicle to keep it from rusting is to fix any paint chips you notice and to wash your vehicle regularly especially in the winter when road salt can promote corrosion as well.

One of the worst places for corrosion to occur was on large ships. From the mid-1800s up to today, most ships have been made of iron. Shipping companies had a constant battle to keep the ships from corroding. They would place sheets of other types of metals over the hull so these sheets would corrode before the iron did. It worked, but it meant that the ships had to go into "dry dock" regularly to have these sheets replaced. Today, the hulls of some ships are built of materials resistant to rust, such as aluminum.

 

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