We explain what a pure substance is, the types that exist and various examples. Also, what are mixtures.
What is a pure substance?
Pure substances are those that have a fixed and defined chemical composition, that is, that does not vary regardless of the physical conditions in which said substance is found. In other words, pure substances remain chemically unaltered (their chemical structure does not change) in their different State of aggregation.
Using physical separation methods the substances Pure cannot be decomposed into simpler substances, nor into their constituent elements. To decompose a pure substance it is necessary to use chemical methods by which the substance is transformed into other substances, or into the elements that compose it.
Furthermore, at a Pressure Y temperature specific, can be reproduced for pure substances, physical properties such as density, the Boiling point and the melting point.
A clear example of a pure substance is the Water, simple and abundant, that can exist in the form liquid, soda or solid, but it will always be composed of the same chemical elements and it will always respond the same to the same conditions of temperature and pressure. On the other hand, if we add salt, sugar and other substances, we alter its physical properties and it is no longer a pure substance.
In nature there is no totally pure substance, that is, substances always have some impurities added. Currently, with scientific and technological advances, it has been possible to purify substances to obtain high degrees of purity.
Types of pure substances
There are two types of pure substances, differentiated from each other based on their atomic composition:
- Simple substances. Pure substances that are made from only one type of atoms, that is, whose molecules they are composed of the same element. For example: helium (He) or oxygen (O2).
- Compound substances. Pure substances that are made up of two or more types of atoms. For example, him Water (H2O) or the carbon dioxide (CO2).
Examples of pure substances
Some examples of pure substances are:
- Water (H2O).
- Ozone (O3).
- Carbon monoxide (CO).
- Carbon dioxide (CO2).
- Pure iron (Fe).
- Sodium (Na).
- Pure gold (Au).
- Benzene (C6H6).
- Graphite (C).
- Salt or sodium chloride (NaCl).
Mixtures
We use mixes constantly in our everyday life.Unlike pure substances, mixtures are made up of several components physically combined, that is, without involving chemical reactions among them.
Mixtures can be separated into their individual components using different separation methods physical that depend on the type of mixture. In this sense, mixtures can be classified into:
- Homogeneous mixtures. Those in which the components of the mixture cannot be distinguished with the naked eye, although they can be separated by certain physical procedures. For example: salt water, cement, blood.
- Heterogeneous mixtures. Those in which the components of the mixture are easily discernible from each other and, therefore, much easier to separate by mechanical or physical procedures. For example: gravel, confetti, water, and oil.