Page 77 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

Reactants :

Products :

The chemical reactions can be represented as equations containing
the symbols and chemical formulae of the reactants and the
products. If so, can the above reaction be represented as

Zn + HCl ZnCl + H
2 2
Now, see how the number of atoms on both sides of the arrow
has been tabulated.

The number of atoms
Atom
Reactants Products
Zn 1 1

H 1 2
Cl 1 2
Table 5.10
Is the number of atoms on both sides of the arrow equal?
The number of identical atoms should be equal on both sides of
the arrow. So let us re-write the equation as follows:
Zn + 2HCl ZnCl + H
2 2
Examine the number of atoms in this equation.

The number of atoms
Atom
Reactants Products
Zn 1 1

H 2 2
Cl 2 2
Table 5.11
Now, isn't the number of atoms of the same kind on both sides of
the arrow equal?

When a chemical equation is written, the number of atoms of the
same kind, on the side of reactants and that of products should be
equal. This type of chemical equations are called balanced chemical
equations.

Basic Science VIII
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