Question

Which of the following is true for solubility of a solid in a liquid ?

• A. Solubility is not affected by changing temperature of the system
• B. Generally, polar solutes readily dissolve in non-polar solvents.
• C. None of the above
• D. Generally, polar solutes readily dissolve in polar solvents.

Answer 1

The correct option is D Generally, polar solutes readily dissolve in polar solvents.

Factors Affecting Solubility:

1. Nature of the solvent & the solute
2. Temperature
3. Pressure

Nature of Solvent & Solute
Like dissolves like. Polar solutes dissolve in polar solvents and non-polar solute dissolve in non-polar solvents.
Example:
Sodium chloride dissolves readily in water, whereas naphthalene and anthracene doesn't.
Naphthalene and anthracene dissolve readily in benzene but sodium chloride doesn't.
Temperature:
$\text{Solute + Solvent}\rightleftharpoons \text{Solution}$
If dissolution is endothermic i.e. $\Delta H<0$
As, the temperature is increasesd, solubility increases.
If dissolution is exothermic i.e. $\Delta H>0$
As, the temperature is increasesd, solubility decreases.

Pressure
Pressure does not have any significant effect on solubility of solids in liquids.
Solids and liquids are highly incompressible and practically remain unaffected by changes in the pressure.