Class 10 Chemistry Chemical Reactions and Equations Balance a chemical equation

How to balance a chemical equation

We take the reaction of formation of water.

H2 + O2 --> H2O (unbalanced equation for formation of water)

This equation can be balanced by using certain steps as mentioned below.

Step I: list the number of atoms of each element present on both sides of arrow.

 

Reactant

Product

H

2

2

O

2

1

 

Step II: Begin balancing with the compound having maximum number of atoms. Following this rule we select H2O. Here there are 2 oxygen atoms on the reactant side but only 1 oxygen atom on the product side. So equation is unbalanced. In order to balance we need to do following step.

 

Reactant

Product

Initial oxygen atom

2

1

To balance

2

1 X 2

So the equation stands out to be

H2 + O2  --> 2H2O

 

Step III: After balancing oxygen the equation is H2 + O2 à 2H2O. So now we need to balance hydrogen atom.

 

Reactant

Product

Initial hydrogen atom

2

4

To balance

2 X 2

4

 So the final equation stands out to be

2H2 + O2 --> 2H2O

 

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