The problems based on chemical equations are of three types:
1. Involving mass-mass relationship.
2. Involving mass-volume relationship.
3. Involving volume-volume relationship.

In order to solve the problems based on chemical equations, keep the following points in mind:

1. Write down the balanced chemical equation.

2. Write down the moles or gram atomic or gram molecular masses of the substances whose quantities are given or have to be found out. In case, there are two or more atoms or molecule of a substance, multiply the gram atomic or gram molecular mass or moles by the number of atoms or molecules.

3. If the volume of a gas is involved in the equation, write down 22·4 litres at S.T.P. below the formula in place of gram molecular mass.

4. Write down the actual quantities of the substances given. For the substances where weights/volumes have to be calculated, just write the sign of interrogation (?) for that.

5. Calculate the result by unitary method.