Question

$20\mathrm{g}$ of sodium chloride is dissolved in water to make up the volume of the solution to $250\mathrm{mL}$. Calculate the mass by volume percentage of sodium chloride in the solution.

Answer 1

A solution comprises of two parts i.e.; solute and solvent

• Solute: The component of the solution to be dissolved or the component present in the solution in the lesser quantity.
• Solvent: The component of the solution that dissolves or the component present in the solution in the larger quantity.

Here, Sodium chloride $\left(\mathrm{NaCl}\right)$ is the solute and Water $\left({\mathrm{H}}_2\mathrm{O}\right)$ is the solvent.

Step-1: Calculate the mass by volume percentage of sodium chloride in the solution

Formula to be used:

$\mathrm{Concentration}\mathrm{in}(\mathrm{m}/\mathrm{v})\%=\frac{\mathrm{Mass}\mathrm{of}\mathrm{the}\mathrm{solute}\left(\mathrm{g}\right)}{\mathrm{Volume}\mathrm{of}\mathrm{the}\mathrm{solution}\left(\mathrm{mL}\right)}\times 100$

• $\mathrm{m}/\mathrm{v}$ represents mass by volume. It is a way to represent the concentration of the solution.
• It is defined as the mass of the solute in $\mathrm{g}$ dissolved in per $100\mathrm{mL}$ of the solution.

Given, mass of the Sodium chloride (solute)= $20\mathrm{g}$

Given, Volume of the solution=$250\mathrm{mL}$

Substituting the given values in the above formula

• $\mathrm{Cancentration}\mathrm{of}\mathrm{Sodium}\mathrm{chloride}(\mathrm{m}/\mathrm{v})\%=\frac{20}{250}\times 100$
• $\mathrm{Cancentration}\mathrm{of}\mathrm{Sodium}\mathrm{chloride}(\mathrm{m}/\mathrm{v})\%=\frac{2000}{250}$
• $\mathrm{Cancentration}\mathrm{of}\mathrm{Sodium}\mathrm{chloride}(\mathrm{m}/\mathrm{v})\%=8\%(\mathrm{m}/\mathrm{v})$