The concentration of a solution may be defined as the amount of solute present in the given quantity of the solution.

The concentration of solution may be expressed in several ways as discussed below:

Mass Percentage

The mass percentage of a component in a given solution is the mass of the component per 100 g of the solution.

\[\text{Mass percentage of a component = }\frac{\text{Mass of the component in the solution}}{\text{Total mass of the solution}} × 100\]

Volume percentage

In the case of a liquid dissolved in another liquid, it is convenient to express the concentrations in volume percentage. The volume percentage is defined as the volume of the component per 100 parts by the volume of the solution.

Mass by volume percentage (w/v)

Sometimes, we express the concentrations as weight/volume. It is the mass of solute dissolved in 100 mL of the solution

Molarity of a solution

The molarity of a solution is defined as the number of moles of the solute dissolved per litre of the solution.It is represented as ′M′. Mathematically,

\[Molarity = \frac{\text{Moles of solute}}{\text{Volume of the solution (in mL)}} × 1000\]

Molarity of a solution

The molarity of a solution is defined as the number of moles of the solute dissolved per litre of the solution.

Molality of the solution

The molality of a solution is defined as the number of moles of the solute dissolved per 1000 g (or 1 kg) of the solvent.

A solution of known normality is diluted to two times. Which of the following changes occur during dilution?

Normality of solute

The correct answer is option 4. Normality of solute.

During dilution of a solution, the following change occurs normality of solute.

Normality \((N)\) of a solution is defined as the number of equivalents of solute present per liter of solution. It is related to the molarity \((M)\) of the solution by the following equation:

\(\text{Normality (N) = } n × M\)

where n is the number of equivalents of the solute per mole of the solute.

When a solution of known normality is diluted, the total number of equivalents of solute remains constant because dilution only involves the addition of more solvent (typically water) to the solution. The amount of solute remains the same, and thus, the number of equivalents of solute remains unchanged during dilution.

However, the volume of the solution increases due to the addition of more solvent, and consequently, the concentration of the solution decreases. As a result, the normality of the solute decreases after dilution.

In summary, during dilution, the normality of the solute changes, while the equivalent of solute, moles of solute, and milli-equivalents or milli-moles of solute remain constant.