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NEET CHEMISTRYMedium

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}^-).

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