Chemical changes


 
 
Concept Explanation
 

Chemical Changes

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. Examples:

  • Reddish – Brown Decomposition on Iron Objects: Iron reacts with atmospheric oxygen in the presence of moisture to form a reddish-brown layer of iron oxide. This layer is called rust and process is called rusting. Oxygen and water are the two essential conditions for rusting of iron. 
  • Browning of Vegetables and Fruit Surfaces: When we exposed the cut surface of a brinjal to the air for some time, the surface has turned brown, due to a chemical reaction between certain compounds present in brinjal and atmospheric oxygen to produce a brown colour pigment “melanin” that cause browning of the surface. 
  • Reaction Between Vinegar and Baking Soda: Vinegar + Baking soda  rightarrow  carbon dioxide + water + other substances. To test carbon dioxide gas, Carbon dioxide + lime water(calcium hydroxide)  rightarrow   calcium carbonate + water.
  • .... (More Text Available, Login?)
    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    Why rusting of iron is a chemical change?

    Right Option : C
    View Explanation
    Explanation
    Question : 2

    The following are generally observed during a process. Which of the above can accompany a chemical change ?

    1. Heat
    2. Sound
    3. Gas
    Right Option : D
    View Explanation
    Explanation
    Question : 3

    Which of the following are correct :

    (a) Iron reacts with atmospheric oxygen in the presence of moisture to form a reddish-brown layer of iron oxide.

    (b) The composition of a substance changes during a chemical change.

    Right Option : C
    View Explanation
    Explanation
     
    Video Link - Have a look !!!
     
    Language - English
     
     
     
    Related Videos
    Language - English
    Language - English
    Language - English

    Language - English
    Language - English

    Language - English
    Language - English
    Language - English

    Language - English
    Language - English

    Language - English

    Language - English



    Students / Parents Reviews [10]