Question

A fellow student does not understand why air is a mixture. Write a brief explanation about why air is a mixture, whether it is homogeneous or heterogeneous, and how it can be separated.

Answer 1

Air is composed of molecules of nitrogen, oxygen and a small amounts of other gases. It is therefore a homogeneous mixture or solution. One way to separate the components is to cool the solution to a liquid and let the various component boil away. (Look up the Linde process.) There are also machines which partially separate (enrich) air. If there is smoke or fog suspended in the air, then it is a heterogeneous mixture