Physical changes VS. chemical changes
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Explanation
In a physical change, the molecules are rearranged while their actual composition remains same.
In a chemical change, the molecular composition of a substance completely changes and a new substance is formed.
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Example
Some example of physical change are freezing of water, melting of wax, boiling of water, etc.
A few examples of chemical change are digestion of food, burning of coal, rusting, etc.
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Reversibility
Physical change is easily reversible i.e original substance can be recovered.
Chemical change is irreversible i.e. original substance cannot be recovered.
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Formation of new substance
In physical change, no new substance is formed.
A chemical change is always accompanied by one or more new substance(s).
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Type of Change
Physical change is a temporary change.
Chemical change is a permanent change.
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Energy Production
In a physical change, no energy is produced.
In a chemical change, energy is produced (heat, light, sound, etc.)
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Absorption of Energy
Physical change involves very little to no absorption of energy.
During chemical reaction, absorption and evolution of energy takes place.
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Affects
Physical change affects only physical properties i.e. shape, size, etc.
Chemical change both physical and chemical properties of the substance including its composition.