It is defined as the representation of reactions taking place between chemicals, with the reactants on the left hand side (L.H.S) and the product obtained from the reaction on the right hand side (R.H.S)

An equation is said to be balanced when there are equal number of molecules for each elements on both sides of the equations.

In the above equation we have, 2 Sodium (Na) and 2 Chlorine (Cl) on both L.H.S and R.H.S, Hence the equation is said to be balanced. llly, an equation is said to be unbalanced when the number of molecules for each elements are not equal on both sides.

Considering the equation above, we have 2 hydrogen (H) and 2 oxygen (O) on the L.H.S and 2 hydrogen (H) and only 1 oxygen (O) on the R.H.S. Hence with the unequal number of oxygen molecules the chemical equation is said to be unbalanced.

Let us learn here how to balance the above unbalanced equation with step by step procedure.

To balance this the unbalanced oxygen molecules, we add 2 in front of the product on R.H.S. We get,

Now, we have 2 Oxygen's but 4 Hydrogen's on the R.H.S. In order to balance the same, we add an another 2 in front of Hydrogen on the L.H.S

Now, the equation is balanced with 4 Hydrogen's (H) and 4 Oxygen's on both sides.

Let us try the same with another example.

Consider the equation,

First table the number of elements on each side to know the imbalance.

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 1 | 1 |

Mn | 1 | 1 |

O | 4 | 1 |

H | 1 | 2 |

Cl | 1 | 5 |

From the table we get that, **K and Mn** are balanced and the elements **O, H and Cl** are not balanced.
First, let us consider balancing Hydrogen molecule (H) as it is required to bring only 1 time on the L.H.S.
To balance H we need to add 2 in front of HCL on the L.H.S
Now, the equation becomes

Now, again table the elements,

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 1 | 1 |

Mn | 1 | 1 |

O | 4 | 1 |

H | 2 | 2 |

Cl | 2 | 5 |

We get, **K, MN and H** are balanced while **O and Cl** are still unbalanced.

Next, let us balance of Oxygen (O). We now have 4 Oxygen's on the L.H.S and 1 on the R.H.S

To balance 'O', we can add 4 in front of water molecule (H_{2}O) on the R.H.S

Now, the equation becomes

by tabling the elements again,

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 1 | 1 |

Mn | 1 | 1 |

O | 4 | 4 |

H | 2 | 8 |

Cl | 2 | 5 |

Now, balance for Cl and H by adding +3 on L.H.S

Table the elements,

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 1 | 1 |

Mn | 1 | 1 |

O | 4 | 4 |

H | 5 | 8 |

Cl | 5 | 5 |

To balance H, add +2 to HCl on R.H.S we get,

Table the elements,

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 1 | 1 |

Mn | 1 | 1 |

O | 4 | 4 |

H | 8 | 8 |

Cl | 8 | 5 |

llly try to balance the number of molecules on both sides of the formula to balance the equation.

Table the elements,

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 1 | 1 |

Mn | 1 | 1 |

O | 4 | 4 |

H | 8 | 8 |

Cl | 8 | 7 |

Now to balance Cl add 2 to KCL on R.H.S

Table the elements

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 1 | 2 |

Mn | 1 | 1 |

O | 4 | 4 |

H | 8 | 8 |

Cl | 8 | 8 |

Now, to balance 'k'

Table the elements

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 2 | 2 |

Mn | 2 | 1 |

O | 8 | 4 |

H | 8 | 8 |

Cl | 8 | 8 |

Now to balance Mn and O, add numbers till the equation becomes balanced.

Table the elements

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 2 | 2 |

Mn | 2 | 2 |

O | 8 | 5 |

H | 10 | 10 |

Cl | 10 | 10 |

Now to balance 'O'

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 2 | 2 |

Mn | 2 | 2 |

O | 8 | 8 |

H | 10 | 16 |

Cl | 10 | 10 |

Now to balance 'H'

Tabling the elements, We get,

Elements | On L.H.S | On R.H.S |
---|---|---|

K | 2 | 2 |

Mn | 2 | 2 |

O | 8 | 8 |

H | 16 | 16 |

Cl | 16 | 16 |

Hence the balanced equation is,