Question 14 Marks
A solution of a solid in a liquid such as water can be prepared by adding it slowly to water with constant stirring at a certain temperature (room temperature). If the addition process is continued, a stage is ultimately reached in the dissolution process when no more of the solid dissolves. Rather it starts setlling at the bottom of the container such as a glass beaker. The solution at this stage is said to be saturated. The solubility of a solute is always expressed with respect to the saturated solution. It may be defined as the maximum amount of the solute that can be dissolved in 100 g of the solvent to form a saturated solution at a given temperature. Please remember that the role of temperature is very important. If temperature is increased, the solution becomes unsaturated. In case the temperature is decreased, the solution becomes supersaturated. As a result, crust of the solute gets deposited on the surface.
i. What do mean by the term Solubility?
ii. 20 g of a solute are dissolved in 500 g of the solvent. The solubility of the solute is:
iii. When a saturated solution becomes unsaturated?
OR
What do you mean by concentration of solution?
i. What do mean by the term Solubility?
ii. 20 g of a solute are dissolved in 500 g of the solvent. The solubility of the solute is:
iii. When a saturated solution becomes unsaturated?
OR
What do you mean by concentration of solution?
Answer
View full question & answer→i. The maximum amount of solute that can dissolve in a given amount of solvent.
ii. Given, Mass of solute $=20 g$Mass of solvent $=500 g$
Mass-Volume percentage $=\frac{20}{500} \times 100$
$
=4 \%
$
Solubility of 500 g of solute $=\frac{4}{100} \times 500$
$
=20 g
$
Hence, the solubility of 20 g of solute in 500 g of solvent is 20 g .
iii. A saturated solution becomes unsaturated by either heating it or by adding more of the solvent.
OR
Concentration of a solution is defined as the amount of solute that is present in a given amount of solution. It can be expressed in terms of: Mass by the mass percentage of a solution $=\frac{\text { mass of solute }}{\text { mass of solution }} \times 100$.
ii. Given, Mass of solute $=20 g$Mass of solvent $=500 g$
Mass-Volume percentage $=\frac{20}{500} \times 100$
$
=4 \%
$
Solubility of 500 g of solute $=\frac{4}{100} \times 500$
$
=20 g
$
Hence, the solubility of 20 g of solute in 500 g of solvent is 20 g .
iii. A saturated solution becomes unsaturated by either heating it or by adding more of the solvent.
OR
Concentration of a solution is defined as the amount of solute that is present in a given amount of solution. It can be expressed in terms of: Mass by the mass percentage of a solution $=\frac{\text { mass of solute }}{\text { mass of solution }} \times 100$.
