Pure Substances and Mixtures

Everything that exists in the earth is a form of a matter which is further defined as any substance that occupies space and has mass. Matter is further divided into various forms such as solid, liquid and gas. Apart from these, it is also classified as pure substances and mixtures. We will learn about the latter in this article.

Pure Substances and Mixtures

Pure Substances

Pure substances are substances that are made up of only one kind of particles and has a fixed or constant structure. Pure substances are further classified as elements and compounds.

An element is a substance that consists of only one type or kind of atom. An element is a pure substance as it cannot be broken down or transformed into a new substance even by using some physical or chemical means. Elements are mostly metals, non-metals or metalloids.

Compounds, on the other hand, are also pure substances when two or more elements are combined chemically in a fixed ratio. However, these substances can be broken down into separate elements by chemical methods.

Characteristics and Properties Of Pure Substances

  • Pure substances are mostly homogeneous in nature containing only one type of atoms or molecules.
  • These substances mainly have a constant or uniform composition throughout.
  • The substances have fixed boiling and melting points.
  • A pure substance usually participates in a chemical reaction to form predictable products.

Examples of Pure Substances

All elements are mostly pure substances. A few them include gold, copper, oxygen, chlorine, diamond, etc. Compounds such as water, salt or crystals, baking soda amongst others are also grouped as pure substances.


A substance, on the other hand, is impure if it consists of different kind of elements combined together physically and not chemically. Impure substances also called mixtures. Mixtures are further divided into a homogenous or heterogeneous mixture.

  • A homogeneous mixture occasionally called a solution, is comparatively unvarying in configuration or constant. Every unit of the mixture is like every other unit. For instance, if you liquefy sugar in water and blend it really well, your concoction is essentially the same no matter where you sample it. This mixture contains two or more chemical substances.
  • A heterogeneous mixture is a concoction whose configuration varies from spot to spot within the sample. For example, if you put a little amount of sugar in a vessel, add some sand, and then shake the jar a couple of times, your concoction doesn’t have the same configuration all throughout the jar. As the sand is heftier, there’s possibly more amount of sand at the bottom of the jar and more sugar at the top part. These mixtures can be identified visually and separated easily by physical means.

Characteristics And Properties Of Mixtures Or Impure Substance

  • It does not have any specific properties, the properties of the mixture are a result of the average properties of all the constituents.
  • It is formed as a result of a physical change.
  • They have a variable composition.
  • Their melting and boiling points differ.

Example Of Mixtures

Some common examples of mixtures include;

  • Gas and gas like nitrogen and oxygen in the atmosphere.
  • A solution like water and oil.
  • Gas and liquid such as water.
  • Solid and liquid such as sand and water

Difference Between Pure Substances and Mixtures

The differences between pure substances and mixture are given below.

Pure Substances Mixtures
Cannot be broken down or separated into new products. Can be separated using different separation methods.
Constant physical and chemical properties. Mixtures have varying physical and chemical properties.
Pure substance consists of a single element. A mixture is a combination of two substances or elements.

Practise This Question

A pipe carrying sewage is called ____________.