Pure substances and mixtures

In a nutshell

A pure substance consists of one element or one compound. A mixture contains two or more different substances.

Pure substances

A pure substance consists of one element or one compound. Pure substances cannot be separated into anything simpler without undergoing a chemical reaction.

Examples

Water molecules and diamond are examples of pure substances. Pure water contains $H_2O$ molecules only. Pure diamond contains the element carbon only.

Mixtures

A mixture contains two or more different substances. It is easy to separate the substances because they are not chemically joined together.

Example

Air is a great example. It consists of a few gases such as nitrogen, oxygen and methane which can all be separated from each other using physical methods.

Tip: Do not confuse mixtures with compounds. Compounds require a chemical reaction to separate them.

Science; Pure and impure substances; KS3 Year 7; Pure substances and mixtures

1.	Pure substance
2.	Mixture of substances