Chemical Reacitons

CHEMICAL REACTIONS 
Another term for chemical change is chemical reaction. There are :rrany kinds of chemical reactions. They may be spectacular and explosive, like the reactions in a fireworks displays. Or they may quite slow, like the formation of rust.
In every chemical reaction, a new substance is produced. A reac­tant is any substance that you start with. A product in a chemical reaction is any substance produced in the action. There may be one or uore reactants and one or more products in a chemical reaction. The products have properties that are different from the properties of the reactants.
In the three chemical reactions above, elements or compounds react to produce a new substance. In another type of chemical reaction, a com­pound breaks down to produce two or more products. For example, when hydrogen peroxide breaks down, it forms water and oxygen.
hydrogen peroxide ---->  water + oxygen
SOME COMMON CHEMICAL REACTIONS 
Chemical reactions are going on all around you. When you cook a hamburger, bake cookies, or allow glue to harden, you are carrying out a chemical reaction. When you eat, the glucose in the food reacts with the oxygen in the air you breathe. This reaction produces the energy you need to run, study, and stay alive.
As you have already learned, rusting of iron is another type of chemical reaction. Rusting is an example of corrosion, or the eating away of metal through a chemical reaction.
Corrosion poses problems in many aspects of life, from bridge con­struction to car manufacturing to the production of computer chips.
Corrosion is a constant problem with boats and ships. Without some protection, the metal parts corrode quickly in water. This is an especially serious problem for ships in salt water.
Paint and other surface coverings can be used to slow corrosion.
Corrosion can also be stopped by fastening reactive metal to a ship or at. A metal that is reactive reacts more easily than other metals. When a reactive metal is attached to a ship, that metal corrodes instead of the more important, less reactive parts of the ship. Zinc and magnesium are two reactive metals used to halt corrosion.
In some metals, corrosion produces a protective surface covering. aluminum is one example. When the surface of a piece of aluminum is scratched, it is shiny, but it soon becomes dull. Some of the alu­minum has combined with oxygen from the air to produce aluminum xide. The aluminum oxide sticks to the surface of the aluminum and protects the rest of it from further reaction. As a result, objects made of aluminum keep their original strength under certain conditions, in :ontrast to iron objects, which are weakened by rusting. Aluminum can therefore be used in making outdoor furniture, snow shovels, and other items exposed to weather. However, pure alu­minum does corrode rapidly in salt water.
Another common type of chemical reaction is combustion, which is another name for burning. Combustion is a chemical reaction in which oxygen is one of the reactants and in which heat is produced. Many substances, such as wood, kerosene, natural gas, and diesel fuel, can undergo combustion. These substances burn easily in air, which is only about 20 percent oxygen. In pure oxygen, they burn much more intensively.

Posted in Chemistry