Question 4
Give an example of each of the following cases (on increasing temperature) (i) solubility increases, (ii) solubility decreases, (iii) solubility remains almost unchanged.
Answer
(i) Solubility increases with an increase in temperature:
- Sugar in water: The solubility of sugar in water increases with increasing temperature. This is because an increase in temperature increases the kinetic energy of the water molecules, which makes it easier for them to break apart and dissolve the sugar molecules.
- Sodium chloride in water: The solubility of sodium chloride in water also increases with increasing temperature. This is because an increase in temperature increases the solubility of ionic compounds in water.
(ii) Solubility decreases with an increase in temperature:
- Oxygen in water: The solubility of oxygen in water decreases with increasing temperature. This is because an increase in temperature decreases the attractive forces between the oxygen and water molecules, making it more difficult for the oxygen molecules to dissolve in the water.
- Carbon dioxide in water: The solubility of carbon dioxide in water also decreases with increasing temperature. This is why carbonated beverages lose their fizziness when they are warmed up.
(iii) Solubility remains almost unchanged with an increase in temperature:
- Calcium sulfate in water: The solubility of calcium sulfate in water remains almost unchanged with an increase in temperature. This is because calcium sulfate is a sparingly soluble salt, and the solubility product is not significantly affected by changes in temperature.
