Class 9 Science Note

Chemical Reaction

Chemical change is the change in which substance loses its properties and form new type of the substance which is different from the properties of the reactants.


Chemical change is brought about by addition, decomposition, exchange of atoms or molecules and the process by which chemical change occurs is called chemical reaction.


If the total number of atoms in the reactants and products are same then the chemical reaction is said to be balancedchemical equation.

For example:

4Al + 3O2        →         2Al2O3

H2 + O2 → H2O
Here, the number of oxygen in the reactant is not equal to the oxygen in product side. So, to balance the equation we have to balance the numbers on the reactant as well as product side.

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