JEE Main · 2024 · Shift-IImediumEC-097

A conductivity cell with two electrodes (dark side) are half filled with infinitely dilute aqueous solution of a weak…

Electrochemistry · Class 12 · JEE Main Previous Year Question

Question

A conductivity cell with two electrodes (dark side) are half filled with infinitely dilute aqueous solution of a weak electrolyte. If volume is doubled by adding more water at constant temperature, the molar conductivity of the cell will: image

Options
  1. a

    decrease sharply

  2. b

    increase sharply

  3. c

    remain same or cannot be measured accurately

  4. d

    depend upon type of electrolyte

Correct Answerc

remain same or cannot be measured accurately

Detailed Solution

Strategy: Analyze the behavior of conductivity in the limit of infinite dilution for weak electrolytes.

Con\ceptual Analysis:

  1. Infinite Dilution: By definition, at infinite dilution, the \degree of dissociation (α\alpha) has already reached its maximum value (11).
  2. Conductivity (κ\kappa) vs. Molar Conductivity (Λm\Lambda_m): Further adding water decreases the number of ions per unit volume, making κ\kappa approach zero.
  3. Molar Conductivity: Λm0\Lambda_m^0 is a constant for a given pair of ions. Doubling the volume from an already "infinite" state doesn't change α\alpha or the ion speed.

Special Case (Half-filled cell): If a cell with fixed electrodes is only half filled, the geometric cell constant GG^* is undefined or doubled in the empty region. Adding water to fill the cell changes the cross-sectional area of the conductor (the solution) between the electrodes, but doesn't change the substan\ce's intrinsic Λm0\Lambda_m^0. Measurement at such low concentrations is extremely difficult.

Answer: (c) remain same or cannot be measured accurately\boxed{\text{Answer: (c) remain same or cannot be measured accurately}}

Practice this question with progress tracking

Want timed practice with adaptive difficulty? Solve this question (and hundreds more from Electrochemistry) inside The Crucible, our adaptive practice platform.

A conductivity cell with two electrodes (dark side) are half filled with infinitely dilute aqueous… (JEE Main 2024) | Canvas Classes