Physical and Chemical Change


 
 
Concept Explanation
 

Physical and Chemical Change

 There can occur two type of changes in a substance. These changes are Physical and Chemical changes.

Physical Changes :

Physical changes are the changes in which no new substance is formed. E.g. the formation of ice from water is a physical change. Physical changes are most of the times for a short span of time, better we can say these changes are temporary and can be reserved. Hence physical change can be defined as: A physical change is the one that changes the shape, size, physical state or appearance of substance but not its chemical composition.

 Characteristics of a physical change :

  • The change is reversible and temporary.
  • No new substance is formed
  • No loss or gain of energy takes place during a physical change.
  • No change in mass occurs during a physical change
  • Examples of physical change :

     Formation of dew, Drying if wet clothes, Breaking of glass, Bending of glass tube, Sublimation of iodine, Crushing of iron, Melting of wax, Crystallization of sugar, Beating aluminum to make aluminum foil , Cutting of nails

    Chemical Change :

    A chemical change occurs when two or more chemical substances react to produce new substance with a different set of properties. It is permanent which cannot be reversed. 

    Characteristics of chemical change :

  • The chemical change is irreversible and permanent.
  • The composition of a substance changes during a chemical change.
  • Either heat is absorbed or evolved during a chemical change.
  • Total mass of the system remains same
  • Example of chemical change 

    Rusting of iron, Burning of candle, Digestion of food, Burning of food, Decomposition of water, Curdling of milk, Butter turning rancid, Ripening of fruit, Drying of paint, Change in color of an apple cut into halves, Clotting of blood, Changes in color of brinjal slice, Digestion of food, Acid base neutralization reaction, Photosynthesis, Removing cream from milk.

    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Which of the following are correct :

    (a) Physical changes are the changes in which no new substance is formed.

    (b) A chemical change occurs when two or more chemical substances react to produce new substance with a different set of properties

    Right Option : C
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    Explanation
    Question : 2

    Which of the following is/are the characteristics of chemical change ?

    Right Option : D
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    Explanation
    Question : 3

    The formation of ice from water is a _____________________ change.

    Right Option : A
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    Explanation
     
     
     
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