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Degree of dissociation (or Ka) of an electrolyte from a measured colligative property

This type of question, asked 6 times: 26 Jun 2022, 29 Jun 2022, 25 Jul 2022, 11 Apr 2023, 8 Apr 2024, 2 Apr 2026 S1. All 6 questions below, oldest first.

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  1. Question 1

    26 Jun 2022

    52
    A 0.5 percent solution of potassium chloride was found to freeze at −0.24∘C-0.24^{\circ}C. The percentage dissociation of potassium chloride is (Nearest integer) (Molal depression constant for water is 1.80 K kg1.80\text{ }K\text{ }kg mol−1mol^{- 1} and molar mass of KClKCl is 74.6 g mol−174.6\text{ }g{\text{ }mol}^{- 1} )

  2. Question 2

    29 Jun 2022

    53
     1.2 mL\ 1.2\text{ }mL of acetic acid is dissolved in water to make 2.0 L2.0\text{ }L of solution. The depression in freezing point observed for this strength of acid is 0.0198∘C0.0198^{\circ}C. The percentage of dissociation of the acid is (Nearest integer) [Given: Density of acetic acid is 1.02 g mL−11.02\text{ }g{\text{ }mL}^{- 1} Molar mass of acetic acid is 60 g mol−160\text{ }g{\text{ }mol}^{- 1}  Kf(H2O)=1.85 K kg mol−1]\left. \ K_{f}\left( H_{2}O \right)= 1.85\text{ }K\text{ }kg{\text{ }mol}^{- 1} \right\rbrack

  3. Question 3

    25 Jul 2022

    33
    The depression in freezing point observed for a formic acid solution of concentration 0.5 mL L−10.5\text{ }mL{\text{ }L}^{- 1} is 0.0405∘C0.0405^{\circ}C. Density of formic acid is 1.05 g mL−11.05\text{ }g{\text{ }mL}^{- 1}. The Van't Hoff factor of the formic acid solution is nearly: (Given for water kf=1.86 K kg mol−1k_{f}= 1.86\text{ }K\text{ }kg{\text{ }mol}^{- 1} )

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  4. Question 4

    11 Apr 2023

    59
    0.004MK2SO40.004MK_{2}SO_{4} solution is isotonic with 0.01M0.01M glucose solution. Percentage dissociation of K2SO4K_{2}SO_{4} is ____(Nearest integer)

  5. Question 5

    8 Apr 2024

    60
    A solution containing 10 g10\text{ }g of an electrolyte AB2AB_{2} in 100 g100\text{ }g of water boils at 100.52∘C100.52^{\circ}C. The degree of ionization of the electrolyte (α)(\alpha) is ______ ×10−1\times10^{- 1}. (nearest integer) [Given : Molar mass of AB2=200 g mol −1.KbAB_{2}= 200\text{ }g\text{ }mol\ ^{- 1}.K_{b} (molal boiling point elevation const. of water) =0.52 K kg mol−1= 0.52\text{ }K\text{ }kg{\text{ }mol}^{- 1}, boiling point of water =100∘C=100^{\circ}C; AB2AB_{2} ionises as  AB2→A2++2 B−]\left. \ AB_{2}\rightarrow A^{2 +}+ 2{\text{ }B}^{-} \right\rbrack

  6. Question 6

    2 Apr 2026 S1

    30
    19.5 g of fluoro acetic acid (molar mass =78 g mol−1= 78\text{ }g{\text{ }mol}^{- 1} ) is dissolved in 500 g of water at 298 K . The depression in the freezing point of water was 1∘C1^{\circ}C. What is KaK_{a} of fluoro acetic acid ? (For water, Kf=1.86 K kg mol−1K_{f}= 1.86\text{ }K\text{ }kg{\text{ }mol}^{- 1} ). Assume molarity and molality to have same values.

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