Mixture They are two or more grouped substances, where the composition is variable and their properties as well. Example of mixtures: blood, milk, air, wood, granite, sugar water.

Some mixtures are so important that they have their own names. Examples are:

- gasoline - mixture of hydrocarbons, which are substances formed by hydrogen and carbon.
- atmospheric air - a mixture of 78% nitrogen, 21% oxygen, 1% argon and other gases such as carbon dioxide.
- hydrated alcohol - 96% mixture of ethyl alcohol plus 4% water.

System It is a part of the universe that one wishes to observe, to analyze. For example: a test tube with water, a piece of iron, a mixture of water and gasoline, etc.

Stages They are the uniform visual aspect. The mixtures may contain one or more phases.

Homogeneous mixture

It consists of only one phase. You cannot differentiate the substance.

- water + salt
- water + ethyl alcohol
- water + acetone
- water + sugar

Water + mineral salts

Heterogeneous Mixture

It is formed by two or more phases. Substances can be differentiated with the naked eye or under the microscope. Examples:

- water + oil
- granite
- water + sulfur
- water + sand + oil

water + oil

Single-phase systems are homogeneous mixtures. Polyphase systems are heterogeneous mixtures.

Homogeneous systems, when formed by two or more miscible (mingling) substances, we call solutions. Examples of solutions are: salt water, vinegar, hydrated alcohol.

Heterogeneous systems can be formed by a single substance, but in several phases of aggregation (physical states).

Example: water
- net
- solid (ice)
- steam