Mixtures

A mixture forms when two or more substances are together but are not chemically bonded to each other. Those substances may be elements, compounds, or both. They are present side by side rather than joined into a new substance.

Because no chemical reaction has combined the substances into something new, each substance keeps its own chemical properties. The substances in a mixture still behave as themselves. For example, in seawater, the water is still water and the salt is still salt.

This is why mixtures can be separated by physical processes. Separating a mixture does not create any new substances. It only sorts out the substances that were already there.

A useful way to recognise a mixture is to look for these features:

• two or more substances are present together;
• they are not chemically bonded;
• each substance keeps its own properties;
• the substances can be separated physically.

Mixtures: examples

• Air is a mixture of gases.
• Seawater is a mixture of water and dissolved salts.
• Sand mixed with salt is a mixture of two solids.