Balance the following equation:

${\mathrm{H}}_2\mathrm{S}+{\mathrm{O}}_2\to {\mathrm{SO}}_2+{\mathrm{H}}_2\mathrm{O}$

Balanced chemical equation: A balanced chemical equation represent the equation in which the number of atom of each element is equal on both the reactant and product side.

Given reaction: $\underset{\mathrm{Hydrogen}\mathrm{sulphide}}{{\mathrm{H}}_2\mathrm{S}}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2}\stackrel{}{\to }\underset{\mathrm{Sulphur}\mathrm{dioxide}}{{\mathrm{SO}}_2}+\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}$

Balancing of chemical reaction:

Step 1: Writing the number of atoms on each reactant and product side

Element	Number of atoms on the reactant side	Number of atoms on the product side
S	1	1
O	2	3
H	2	2

Oxygen (O) is unbalanced in the above chemical reaction.

Step 2: Balancing the Oxygen atoms

Multiply the Oxygen by 3 on the reactant side; Sulphur dioxide and water by 2 on the product side.

$\underset{\mathrm{Hydrogen}\mathrm{sulphide}}{{\mathrm{H}}_2\mathrm{S}}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2}\stackrel{}{\to }\underset{\mathrm{Sulphur}\mathrm{dioxide}}{2{\mathrm{SO}}_2}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}$

Step 3: Balancing the other unbalanced atoms

Now, the Hydrogen and Sulphur atoms are unbalanced. So, balance them by multiplying hydrogen sulphide on the reactant side by 2.

$\underset{\mathrm{Hydrogen}\mathrm{sulphide}}{2{\mathrm{H}}_2\mathrm{S}}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2}\stackrel{}{\to }\underset{\mathrm{Sulphur}\mathrm{dioxide}}{2{\mathrm{SO}}_2}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}$

Element	Number of atoms on the reactant side	Number of atoms on the product side
S	2	2
O	6	6
H	4	4

All the elements have an equal number of atoms.

Thus, the balanced chemical equation is $\underset{\mathrm{Hydrogen}\mathrm{sulphide}}{2{\mathrm{H}}_2\mathrm{S}}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2}\stackrel{}{\to }\underset{\mathrm{Sulphur}\mathrm{dioxide}}{2{\mathrm{SO}}_2}+2\underset{\mathrm{Water}}{{\mathrm{H}}_2\mathrm{O}}$