Which one of the following statements is false?(AIEEE 2004)a)Raoults l...
But CH3COOH is weak electrolyte than KCI.
i for sucrose is 1 as it is a non-electrocyte.
Thus, i for BaCI2> KCI > CH3COOH > sucrose Thus, (c) is also true.
(d) ΔTf = Kfm.
Kf is dependent on solvent.
Thus, freezing points = [T (solvent) - ATf] are different.
Thus, (d) is false.
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Which one of the following statements is false?(AIEEE 2004)a)Raoults l...
False Statement:
- Two sucrose solutions of the same molality prepared in different solvents will have the same freezing point depression.
Explanation:
1. Raoult's Law:
- Raoult's law states that the vapor pressure of a component over a solution is proportional to its mole fraction.
- The vapor pressure of a component in a solution is lower than its pure form due to the presence of other components.
- The decrease in vapor pressure is directly proportional to the mole fraction of the solute.
- Hence, statement (a) is true.
2. Osmotic Pressure:
- The osmotic pressure (π) of a solution is given by the equation π = MRT, where M is the molarity of the solution.
- Osmotic pressure is the pressure required to stop the flow of solvent molecules across a semipermeable membrane.
- It depends on the concentration of solute particles and temperature.
- Therefore, statement (b) is true.
3. Order of Osmotic Pressure:
- The correct order of osmotic pressure for a 0.01 M aqueous solution of each compound is BaCl2 > KCl > CH3COOH > sucrose.
- Osmotic pressure is directly proportional to the concentration of solute particles.
- BaCl2 dissociates into three particles (Ba2+ and 2Cl-) in solution, KCl dissociates into two particles (K+ and Cl-), CH3COOH partially dissociates into two particles (CH3COO- and H+), and sucrose does not dissociate.
- Therefore, BaCl2 will have the highest osmotic pressure followed by KCl, CH3COOH, and sucrose.
- Hence, statement (c) is true.
4. Freezing Point Depression:
- The freezing point depression is a colligative property that depends on the number of solute particles present in a solution.
- The freezing point depression (∆Tf) is given by the equation ∆Tf = Kf * m * i, where Kf is the cryoscopic constant, m is the molality of the solution, and i is the van't Hoff factor.
- The van't Hoff factor represents the number of particles into which a solute dissociates in a solution.
- Different solvents have different solute-solvent interactions, which affect the degree of dissociation and the van't Hoff factor.
- Therefore, two sucrose solutions of the same molality prepared in different solvents will have different freezing point depressions.
- Hence, statement (d) is false.
Conclusion:
- The false statement among the given options is (D) - "Two sucrose solutions of the same molality prepared in different solvents will have the same freezing point depression."
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