Physical and Chemical Changes
Everything in the universe is made up of small tiny particles which have physical and chemical properties.Physical properties include odor,taste,appearance,melting point,boiling point etc.. where as chemical properties include the chemical reaction,changes at molecular level.Every thing in the universe undergoes either physical change or chemical change.
PHYSICAL CHANGE: When the matter or substance changes in its physical properties we can say it is undergoing physical change. 1. During the physical change neither the chemical composition nor chemical nature of the substance changes.
For example:Tearing a paper is a physical change because when the paper is torn only the appearance of paper is changed.
2.Physical changes are reversible.
For example: Phase changes of water.If water is freezed it converts into ice cube , if we melt the ice cube it converts into water again. this says
physical changes are reversible.
3.No new substance is formed.
for example:If we tear a paper into pieces , it is still a physical change because the pieces of paper are still a part of paper.
CHEMICAL CHANGE: when the matter or substance change in its chemical properties we can say it is undergoing chemical change. 1.During the chemical change the chemical properties of matter changes.
For example:The conversion of milk into curd.
2.Chemical changes are irreversible:
For example: Rotting of fruits.
3.New substance is formed
For example:If we burn a piece of paper it is converted into ash. Ash is the new substance formed here.