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NEET CHEMISTRYElectrochemistryEasy

Question

At 25C25^{\circ} \text{C} molar conductance of 0.1 molar0.1 \text{ molar} aqueous solution of ammonium hydroxide is 9.54 ohm1cm2mol19.54 \text{ ohm}^{-1} \text{cm}^2 \text{mol}^{-1} and at infinite dilution its molar conductance is 238 ohm1cm2mol1238 \text{ ohm}^{-1} \text{cm}^2 \text{mol}^{-1}. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is

A

2.080%2.080\%

B

20.800%20.800\%

C

4.008%4.008\%

D

40.800%40.800\%

Step-by-Step Solution

The degree of dissociation (α\alpha) of a weak electrolyte is the ratio of its molar conductivity at a given concentration (Λmc\Lambda_m^c) to its limiting molar conductivity at infinite dilution (Λm\Lambda_m^\infty).

Given: Molar conductance at concentration cc, Λmc=9.54 ohm1 cm2 mol1\Lambda_m^c = 9.54 \text{ ohm}^{-1} \text{ cm}^2 \text{ mol}^{-1} Molar conductance at infinite dilution, Λm=238 ohm1 cm2 mol1\Lambda_m^\infty = 238 \text{ ohm}^{-1} \text{ cm}^2 \text{ mol}^{-1}

Degree of dissociation (α\alpha) =ΛmcΛm= \frac{\Lambda_m^c}{\Lambda_m^\infty} α=9.54238=0.04008\alpha = \frac{9.54}{238} = 0.04008

To find the percentage degree of ionisation: α%=0.04008×100%=4.008%\alpha \% = 0.04008 \times 100\% = 4.008\%

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Electrochemistry. 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.

CHEMISTRYElectrochemistryconductanceaqueoussolutionammoniumhydroxide

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