UPSC Civil Services (Mains), Chemistry optional · 2022 · Paper I

Q3(e). Forces on an ion moving through a strong-electrolyte solution

10 marks
Topic: Electrochemistry
Answered

Question

Provide briefly a qualitative account of different forces which influence the speed of an ion in solution of strong electrolyte moving under an externally applied electric field.

Answer in brief

Four forces act: the electric force drives the ion, while the viscous drag of the solvent, the relaxation (asymmetry) force and the electrophoretic force hold it back; the last two come from the ionic atmosphere.

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Read the whole 2022 solution 2022 question paper

Topic notes: electrolytic conductance, Kohlrausch's law, transport numbers and the Debye–Hückel limiting law, with every Civil Services, IFoS and Geo-Scientist PYQ →

CoversDebye–Hückel–Onsager theoryrelaxation effectelectrophoretic effectionic atmosphereOnsager equationWien effect

All parts of Question 3

3(a) The least stable of OCN⁻, ONC⁻ and SCN⁻10 marks
3(b) Entropy changes when an ice cube melts in the sea at 0 °C10 marks
3(c) Speed distribution curves of argon and helium10 marks
3(d) Phase diagram of water; critical point and triple point10 marks
3(e) Forces on an ion moving through a strong-electrolyte solution10 marks