UKPCS Science Chemistry: Physical change and Chemical change #41

Oracle IAS, the best coaching institute for UPSC/IAS/PCS preparation in Dehradun brings to you UKPCS Science Chemistry (paper 6). 

Comparison Chart- Physical change and Chemical change

Meaning Physical change refers to a change in which the molecules are rearranged but their internal composition remains same. Chemical Change is a process in which the substance transforms into a new substance, having different chemical composition.
Example Tearing of paper, melting/freezing of water, cutting of trees, etc. Burning of wood/trees/paper, rusting of iron, setting of curd, etc.
Nature Reversible Irreversible
Original matter Can be recovered Cannot be recovered
Involves Change in physical properties of the substance, i.e. shape, size, color etc. Change in chemical properties and composition of the substance.
Product Formation No new product is formed. New product is formed.
Energy Absorption and evolution of energy do not take place. Absorption and evolution of energy take place, during reaction.


Example of both changes occurring simultaneously:

  • Burning of candle: While melting of wax is a physical change, as the state of the substance changes from solid to liquid, burning of wax is a chemical change, as after consuming energy from wax, light lits up.
  • Cooking of food: Cooking of raw vegetables or grains is a chemical change and transformation of water into steam is a physical change.


To sum up, physical change is any change that only transforms the substance’s physical properties, but chemical change results in the change in the chemical structure of the substances involved.

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