what is a chemical reaction? what changes occure in a chemical reaction? give 5-6 examples of a chemical reaction.
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Answered by
9
Heya...
Here is your answer --
A change which alters the specific properties of a material by bringing about a change, is called a chemical change. On the other hand we can say that when two or more substances react in such a way that there is formation of one or more new substances, the change is called a chemical change or chemical reaction.
CHARACTERISTICS OF A CHEMICAL CHANGE :-
(i) Evolution of gas
For example :
• When Zinc granules are added to dilute sulphuric acid, hydrogen gas is evolved. If a burning matchstick is brought near the mouth of a test tube, it burns with a pop sound.
Sulphuric acid + Zinc --> Zinc Sulphate + Hydrogen
(ii) Change of colour
For example :
• When solid lead nitrate is heated, reddish-brown nitrogen oxide is evolved. Also, a yellow coloured lead monoxide is formed.
Lead nitrate --> (heat supply) Nitrogen dioxide (reddish-brown) + lead oxide (yellow) + oxygen
(iii) Formation of Precipitate
For example :
• When hydrogen sulphide gas is passed through blue coloured copper Sulphate solution, black Precipitate of copper sulphide is formed.
Copper Sulphate + hydrogen sulphide --> Copper sulphide + sulphuric acid
(iv) Absorption or evolution of heat
For example :
• When water is added to quicklime, heat energy is evolved.
Quicklime + Water --> Calcium hydroxide + heat
(v) Sound may be produced
For example :
When baking soda is added to vinegar, carbon dioxide gas is produced with a hissing sound.
Vinegar + Baking Soda --> Carbon dioxide + Hissing sound
HOPE IT HELPS...!!
Here is your answer --
A change which alters the specific properties of a material by bringing about a change, is called a chemical change. On the other hand we can say that when two or more substances react in such a way that there is formation of one or more new substances, the change is called a chemical change or chemical reaction.
CHARACTERISTICS OF A CHEMICAL CHANGE :-
(i) Evolution of gas
For example :
• When Zinc granules are added to dilute sulphuric acid, hydrogen gas is evolved. If a burning matchstick is brought near the mouth of a test tube, it burns with a pop sound.
Sulphuric acid + Zinc --> Zinc Sulphate + Hydrogen
(ii) Change of colour
For example :
• When solid lead nitrate is heated, reddish-brown nitrogen oxide is evolved. Also, a yellow coloured lead monoxide is formed.
Lead nitrate --> (heat supply) Nitrogen dioxide (reddish-brown) + lead oxide (yellow) + oxygen
(iii) Formation of Precipitate
For example :
• When hydrogen sulphide gas is passed through blue coloured copper Sulphate solution, black Precipitate of copper sulphide is formed.
Copper Sulphate + hydrogen sulphide --> Copper sulphide + sulphuric acid
(iv) Absorption or evolution of heat
For example :
• When water is added to quicklime, heat energy is evolved.
Quicklime + Water --> Calcium hydroxide + heat
(v) Sound may be produced
For example :
When baking soda is added to vinegar, carbon dioxide gas is produced with a hissing sound.
Vinegar + Baking Soda --> Carbon dioxide + Hissing sound
HOPE IT HELPS...!!
aishowrya:
Awesome ^^
thanks ... ;-p
Answered by
6
Chemical reaction is a reaction in which the properties of the substance formed is different from the original one. Chemical reaction is usually not reversible.
For example --> Rusting of iron
burning of paper
burning of wool
For example --> Rusting of iron
burning of paper
burning of wool
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