Definition of Mixture

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.

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