Explain the concept of reactions in solutions and mass percentage.

(N/A) majority of chemical reactions in laboratories are carried out in solutions. Therefore,it is important to understand how the amount of substance is expressed when it is present in the form of a solution. The concentration of a solution or the amount of substance present in its given volume can be expressed in the following ways:
$(i)$ Mass percent or weight percent $(w/w \%)$
$(ii)$ Mole fraction
$(iii)$ Molarity
$(iv)$ Molality
Mass percent is defined as the mass of the solute per $100 \ g$ of the solution.
$\text{Mass percent} = \frac{\text{Mass of solute}}{\text{Mass of solution}} \times 100$