What is a Mixture?
A mixture contains two or more substances that are not chemically combined.
Mixtures are unlike chemical compounds, because:
- The substances in a mixture can be separated using physical methods such as filtration, freezing, and distillation.
- There is little or no energy change when a mixture forms.
- Mixtures have variable compositions, while compounds have a fixed, definite formula.
- When mixed, individual substances keep their properties in a mixture, while if they form a compound their properties can change.
Examples of Common Mixtures:
- Sea water - a mixture of water and various salts.
- Crude oil - a mixture of organic compounds - mainly hydrocarbons.
- Gunpowder - a mixture of potassium nitrate, sulfur and carbon.
- Dry Air - a mixture of nitrogen, oxygen, argon, carbon dioxide, neon and tiny traces of other gases. (Air normally also contains water vapor as part of the mixture.)
- Ink - a mixture of colored dyes which can be separated using chromatography.
It's possible to get homogeneous mixtures and heterogeneous mixtures.