Consider the given plots of vapor pressure (VP) vs temperature (T/K). Which amongst the following options is the correct graphical representation showing $ \Delta T_f $ depression in the freezing point of solvent in a solution?

Question

$W$ g of a non-volatile electrolyte solid solute of molar mass $M\,\text{g mol}^{-1}$ when dissolved in $100\,\text{mL}$ water decreases vapour pressure of water from $640\,\text{mm Hg}$ to $600\,\text{mm Hg}$. If aqueous solution of the electrolyte boils at $375\,\text{K}$ and $K_b$ for water is $0.52\,\text{K kg mol}^{-1}$, then the mole fraction of the electrolyte $(x_2)$ in the solution can be expressed as ___.
(Given: density of water $=1\,\text{g mL}^{-1}$, boiling point of water $=373\,\text{K}$)

Answer 1

To comprehend the graphical illustration of freezing point depression in a solvent due to solute addition, understanding colligative properties is fundamental. Freezing point depression is a colligative property demonstrating how solute presence alters solvent characteristics. Solute addition reduces the solvent's vapor pressure, consequently lowering its freezing point.

Concept Explanation:
- Adding a non-volatile solute to a solvent disrupts the solvent's crystalline structure, reducing its freezing point relative to the pure solvent. This is termed freezing point depression ($\Delta T_f$).
- The presence of a solute lowers the solvent's vapor pressure. At the freezing point, solid and liquid phases coexist in equilibrium.
- Deviations from ideal vapor pressure behavior at varying temperatures cause a shift in the freezing point.
Graphical Representation:
- Seek a graph depicting a reduction in freezing point upon solute addition. Identify a graph where the solution's vapor pressure curve intersects the solid line at a lower temperature than the pure solvent's.
Analyzing Options:
- The accurate graph will show the solution's vapor pressure below that of the pure solvent, resulting in an intersection with the solid phase line at a reduced temperature, consistent with freezing point decrease ($\Delta T_f$).
- Locate this graph among the given choices. The correct depiction is:
Conclusion:
- This graph illustrates the solution's vapor pressure curve intersecting the solid state line at a temperature lower than that of the pure solvent. It accurately represents the freezing point depression ($\Delta T_f$) caused by solute addition.

Consider the given plots of vapor pressure (VP) vs temperature (T/K). Which amongst the following options is the correct graphical representation showing \( \Delta T_f \) depression in the freezing point of solvent in a solution?

Show Hint

The Correct Option is C

Solution and Explanation

Top Questions on Colligative Properties

Questions Asked in JEE Main exam