Class 6 Chemistry Changes around us Types of Changes

Types of Changes

  • Changes around us can be grouped as those that can be reversed (reversible change) and those that cannot be reversed (irreversible changes).
  • Reversible change:
    • A change in which original substance can be recovered.
    • Examples of some reversible changes:-
      • Folding of paper
      • Rolling out a chapatti from a ball of dough.
      • Stretching of rubber to its normal size.
      • Melting of ice candy
      •  Class_6_Chemistry_Changes_Around_Us_Rolling_Of_Chapatti
      • Class_6_Chemistry_Changes_Around_Us_Folding_Of_Paper 
        • Irreversible change: -
          • A change in which the original substance cannot be recovered.
          • Examples of some irreversible changes:-
            • Ripening of fruits
            • Souring of milk
            • Cooking of food
            • Burning of paper
            • Cutting of paper
          • Class_6_Chemistry_Changes_Around_Us_Changing_State
          • Physical Change: -
            • A change brought about the physical properties of a substance.
            • No new substance is formed.
            • Molecular composition of the substance remains the same.
            • Shape, size, colour changes.
            • Most of physical changes are reversible.
            • Heat involved is less.
              • Examples: - Melting of ice, glowing of an electric bulb etc.
            • Chemical Change: -
              • A change that produces entirely new substances with different chemical properties.
              • Molecular composition of the substance changes.
              • More heat is absorbed and liberated.
              • Most of chemical changes are permanent and irreversible.
                • Examples: - Digestion of food, Ripening of Food etc.

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