Pure Substance or Mixture

Matter can be classified as either a pure substance or a mixture.

So let’s take a look at the difference between the two.

A pure substance is either an element or a compound. All of the elements found on the periodic table are pure substances. They cannot be chemically separated. 

Compounds which are elements bonded together are also pure substances.

For example, water contains two hydrogen elements bonded to one oxygen.

Carbon dioxide is two oxygens bonded to carbon. They require a chemical process to separate the compound.There are millions of compounds found in the world.

Mixtures on the other hands are a combination of substances that can be separated physically.

There are two kinds of mixtures, homogeneous mixtures and heterogeneous mixtures. 

A mixture that is uniform, or the same throughout is a homogeneous mixture. You often hear them referred to as solutions.

Some common examples include,

• Gatorade
• Gasoline,
• Alloys like brass which is a mixture of copper and zinc

A heterogeneous mixture is one that is not uniform and is different throughout.

Examples include a

• Fruit salad
• Oil and vinegar
• Soil

Here is a simple flow chart to help you classify something as a pure substance or a mixture

Can it be separated physically ?    No it's a pure substance 

Can it be separated by a chemical process? no it is an element  yes it is a compound

Can it be separated physically?  yes it is a mixture

Is it uniform throughout? yes it is a homogeneous mixture  no it is a heterogeneous solution.

Rates of Reaction

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