Purification of surface water
When the shape, size, appearance or state, of a substance is altered, but its chemical composition remains same a physical change of matter takes place. No new substance is formed. It is usually a change, which is reversible. Such as: preparing a solution, breaking a glass tumbler, glowing a electric bulb, etc.
Examples of Physical Changes
- By using a piece of gold, a goldsmith can make a gold chain and can later alter it to make a gold bracelet, ring or a pair of earrings. All of them consist of the same substance, namely gold. This is an example of a physical change.
- A more common everyday example is that of water, which can be converted into solid ice, liquid water, and gaseous water vapour. It can be reconverted to its previous state by various methods. Yet, in all the three forms, the chemical composition of water is not altered. No new substance with new chemical properties is formed. In all these, water consists of two atoms of hydrogen and one atom of oxygen.
- Dissolving of sugar in water when crystalline sugar is dissolved in water, it seems to disappear completely and not even a very powerful microscope can show us the molecules of sugar in water. The solution obtained is uniformly sweet. By evaporating the water the sugar can be recovered in a crystalline form.
A physical change involves a change in the physical state of a substance by changing either the inter particle spaces or inter particle forces.
- There is no change in the composition of the substances during the physical change.
- The substances undergoing physical changes do not change their main characteristics.
- No new substance is formed during physical change.
- The change is temporary and can be reversed by reversing the conditions which bring about the change.