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NEET CHEMISTRYSolutionsMedium

Question

A 0.0020 m0.0020 \text{ m} aqueous solution of an ionic compound Co(NH3)5(NO2)Cl\text{Co(NH}_3)_5(\text{NO}_2)\text{Cl} freezes at 0.00732C-0.00732^\circ\text{C}. Number of moles of ions which 1 mol1 \text{ mol} of ionic compound produces on being dissolved in water will be (Kf=1.86C m1K_f = 1.86^\circ\text{C m}^{-1})

A

2

B

3

C

4

D

1

Step-by-Step Solution

Given: Molality of the solution (mm) = 0.0020 m0.0020 \text{ m} Freezing point of the solution = 0.00732C-0.00732^\circ\text{C} Depression in freezing point (ΔTf\Delta T_f) = 0C(0.00732C)=0.00732C0^\circ\text{C} - (-0.00732^\circ\text{C}) = 0.00732^\circ\text{C} Molal depression constant (KfK_f) = 1.86C m11.86^\circ\text{C m}^{-1}

The formula for depression in freezing point is: ΔTf=i×Kf×m\Delta T_f = i \times K_f \times m Where ii is the van't Hoff factor (which represents the number of moles of particles produced per mole of the solute).

Substituting the given values into the equation: 0.00732=i×1.86×0.00200.00732 = i \times 1.86 \times 0.0020 0.00732=i×0.003720.00732 = i \times 0.00372 i=0.007320.003721.9672i = \frac{0.00732}{0.00372} \approx 1.967 \approx 2

Thus, 1 mol1 \text{ mol} of the ionic compound produces 22 moles of ions in the solution. (The complex most likely ionizes as: [Co(NH3)5(NO2)]Cl[Co(NH3)5(NO2)]++Cl[\text{Co(NH}_3)_5(\text{NO}_2)]\text{Cl} \rightleftharpoons [\text{Co(NH}_3)_5(\text{NO}_2)]^+ + \text{Cl}^-).

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Solutions. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

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