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Take a look at this image. What do you observe?
Here 2 substances react with each other to form 2 new substances .
This is called a Chemical Reaction .
Let us take a look at the different aspects of Chemical Reactions.
What are Reactants and Products ?
During a chemical reaction, one or more substances react with each other (change) to produce one or more other substances
The substances which undergo chemical change are called Reactants
The substances formed after the reaction are called Products
Example 1:
When Calcium Carbonate is heated,it produces Calcium oxide and Carbon Dioxide
Calcium Carbonate−−−−−−> Calcium Oxide + Carbon Dioxide
1 1st 2nd
Reactant Product Product
Example 2:
Hydrogen and Oxygen combine to form Water
What is Law of Conservation of Mass
What do you observe in the image above?
During a chemical reaction, the sum of the masses of the
reactants and products remain unchanged.
This is known as the Law of Conservation of Mass
As per this law ,
Matter can never be created nor destroyed
Total Mass of Reactants = Total Mass of Products
Example 1
When 100 grams of calcium carbonate is heated,it produces 56 grams of Calcium oxide and 44 grams of Carbon Dioxide
Calcium Carbonate −−−−−−> Calcium Oxide + Carbon Dioxide
1 1st 2nd
Reactant Product Product
(100 grams) 56 grams 44 grams
Total =56+44=100 grams
Total Mass of Reactants = Mass of Calcium Carbonate = 100 grams
Total Mass of Products = Mass of Calcium + Mass of Carbon Dioxide = 56 + 44 = 100 grams
Hence,
Total Mass of Reactants = Total Mass of Products
We can say that the sum of masses of reactants and products remain unchanged.
Note:
Law of conservation of Mass can be applied to Physical Changes also
Example
If 100 grams of ice is melted, it produces 100 grams of water
Ice −−−−−−−−−−−> Water
100 grams 100 grams
1 1
Reactant Product
Here also we can see that mass of initial and final stage of matter is the same
SAMPLE PROBLEM 1 LS PG 112
Example -
In text Quention - Page 32 Q1
NCERT Question - Q1
