(a) Out of the following pairs, predict with reason which pair will allow greater conduction of electricity:
(i) silver wire at 30°C or silver wire at 60°C;
(ii) 0.1 M CHCOOH solution or 1 M CHCOOH solution;
(iii) KCl solution at 20°C or KCl solution at 50°C.
(b) Give two points of difference between electrochemical and electrolytic cells.
(i) silver wire at 30°C or silver wire at 60°C;
(ii) 0.1 M CHCOOH solution or 1 M CHCOOH solution;
(iii) KCl solution at 20°C or KCl solution at 50°C.
(b) Give two points of difference between electrochemical and electrolytic cells.
Solution
(a)(i) Silver wire at 30°C. Metallic (electronic) conduction decreases with rising temperature, since increased thermal vibration of the metal kernels scatters the electrons.
(ii) 1 M CHCOOH. Conductivity counts ions per unit volume; though the degree of dissociation is lower, the concentrated solution still holds more ions per cm than the 0.1 M solution.
(iii) KCl solution at 50°C. Electrolytic conduction increases with temperature — the ions move faster and ion–solvent attractions weaken.
(b) Electrochemical (galvanic) cell: converts the energy of a spontaneous redox reaction into electricity; the anode is the negative electrode; the two half-cells are usually separate, joined by a salt bridge.
Electrolytic cell: uses external electricity to drive a non-spontaneous reaction; the anode is the positive electrode; both electrodes sit in the same electrolyte.
(ii) 1 M CHCOOH. Conductivity counts ions per unit volume; though the degree of dissociation is lower, the concentrated solution still holds more ions per cm than the 0.1 M solution.
(iii) KCl solution at 50°C. Electrolytic conduction increases with temperature — the ions move faster and ion–solvent attractions weaken.
(b) Electrochemical (galvanic) cell: converts the energy of a spontaneous redox reaction into electricity; the anode is the negative electrode; the two half-cells are usually separate, joined by a salt bridge.
Electrolytic cell: uses external electricity to drive a non-spontaneous reaction; the anode is the positive electrode; both electrodes sit in the same electrolyte.
CBSE Class 12 Board · 2020 · Subjective