Question

5 points of difference between physical and chemical change

Answer 1

☆Physical changes are changes which are reversible. Chemical changes are changes which are irreversible.

☆In a Physical change, the composition or properties of the substance is not altered. In a Chemical change, the composition and properties of the substance is altered.

☆A Physical change is temporary. A Chemical change is permanent.

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• There is no gain or loss of energy during a Physical change. Energy required for completion of a Physical change is released when the change is reversed.

• Energy is either absorbed or evolved during a Chemical change. Energy in the form of light, percussion [pressure] or generally heat energy is required for a Chemical change.

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• In Physical change, there is no change in mass of the substance undergoing a Physical change. Reason: No matter is added or removed during a Physical change.

• In Chemical change, there is change in mass of the substance undergoing a Chemical change. Reason: Matter is added or removed but total mass unaltered.

☆ New substance is not formed in Physical change. New substance is formed in Chemical change.

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• Examples of Physical change- Melting of wax, Boiling of milk, Rain Cycle, etc.

• Examples of Chemical change- Carbon Cycle, Ripening of a fruit, Curdling of milk, etc.

Hope it helps! :)