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States of matter – chemistry revision notes

This post briefly discusses the states of matter with their important characteristics. We also define the Triple point with one example.

Three States Of Matter – with characteristics

Matter exists in three different physical states, namely solid, liquid and gaseous states. The important characteristics of the three states are:

Solid state: A solid possesses a definite size (volume) and a definite shape. The shape of a solid can be changed but it usually requires considerable force. Therefore, solids are generally hard and rigid. Some common examples of solids are iron, silver, common salt, etc.

Liquid state: A liquid possesses a definite volume but not a definite shape. It takes up the shape of the container in which it is placed. Liquid also has a tendency to flow. For example, water, alcohol, milk, oil, etc.

Gaseous state: A gas neither possesses a definite volume nor a definite shape. A gas occupies the whole volume of the vessel in which it is placed. It also takes up the shape of the container. For example, air, carbon dioxide, oxygen, hydrogen, etc.

However, it may be noted that a substance may exist in any of the three states under appropriate conditions of temperature and pressure. As we all know, water can exist in three states of matter as ice (solid), water (liquid), or steam (gas).

What is Triple point?

The temperature at which all the three phases of the same substance exist simultaneously is called the triple point.

It may be noted that a given substance may also exist simultaneously in all three states under certain specific conditions of temperature and pressure. For example, water exists in all three phases simultaneously i.e. ice, water, and water vapour at 0.01°C and 4.58 mm of Hg pressure.

See also  Enthalpy - chemistry revision notes for class 11

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