According to the Encyclopedia Britannica, ammonia is a pure substance because it is a compound of the elements nitrogen and hydrogen. The two elements are joined chemically, so it cannot be considered a mixture. More »

Gasoline is a homogeneous mixture made from processing or refining crude oils. A homogeneous mixture consists of combinations of different substances. However, a homogeneous mixture also has uniform composition and prope... More »

Air is a mixture, which is primarily made up of nitrogen and oxygen. It is more nitrogen than oxygen, with about 78 percent of the makeup being the nitrogen and 21 percent oxygen. More »

A pure substance contains only one kind of molecule, and a mixture is a combination of two or more pure substances. Distilled water, aluminum foil and table sugar are each made from only one type of particle. However, sa... More »

Metal alloys, which are a mixture of metal and at least one other substance, are used because they are more suited for a particular task than a pure metal is. Metal alloys are typically either harder, stronger, lighter o... More »

You can compare and contrast mixtures and pure substances by determining if the substance can be separated into homogeneous materials. Determine if the substance can be changed into a different substance as well. More »

Air is not a pure substance but a mixture of different gases. It is composed of approximately 78 percent nitrogen and 21 percent oxygen, with small amounts of about a dozen other gases making up the remainder. More »