Important Questions of Electrochemistry
1. (a) What is the difference between metallic and electrolytic conduction?
(b) What do you understand by (i) Electrolytic conductance (ii) Specific conductance.
2. Explain the following:
(i) Conductance of an electrolytic solution increases with temperature where as that of a metal decreases.
(ii) Specific conductance decreases on dilution of an electrolyte whereas equivalent conductance increases.
(iii) Significance of Kohlrausch’s law of independent migration of ions.
3. State and explain Kohlrausch’s law of independent migration of ions. How do you experimentally determine the degree of dissociation of a weak electrolyte in solution?
4. Describe briefly the Arrhenius theory of electrolytic dissociation. What are its limitations?
5. State and explain the Ostwald’s dilution law. Why is the law not applicable in case of strong electrolytes?
What is the transport number of an ion? Describe (1) Hittorts method. (2) Moving boundary method employed in determining the transport number of an ion.
A contain current was passed through a solution of AuCI; ions between gold electrodes. After a period of 10.00 minutes the cathode increased in weight by 1.314 grams. How much charge was passed and what was the current I?
Ans: q= 2×104Faraday. I= 3.22Ampere.
The measured resistance of a cell containing exactly 0.1g. equivalent of KC1 in 1000 ml. at 25 °C was found to be 3468.9 ohms; the specific conductance of. the solution is known to be 0.012855011m-I cnii at 25°C. An exactly 0.1 N solution of another substance in the same cell had a resistance of 4571.5 ohms. Calculate the equivalent conductance of this electrolyte at the given concentration. (The conductance of the water is so small that it may be neglected.) Ans: A = 97.51 ohnilcm-I.
A solution of AgNO3 containing 0.0074 g per gram of water was electrolysed using silver electrodes. During the experiment, 0.0785 g of Ag was deposited in a silver voltameter. At the end of electrolysis, 25 g of anode solution contained 0.2553 g of AgNO3. Calculate the transport number of NO3– ion. (Atomic weight of Ag = 108; N-14, 0=16) Ans. 0.569.
The transference numbers of the ions in 1.00N KCI were determined by the moving boundary method using 0.8014 BaC12 as the following solution. With a current of 0.0142 amp., the time required for the boundary to sweep through a value of 0.1205c.c. was 1675 sec. What are the transport numbers-of le and Cr ions? Ans; t.= 0.40. 1= 0.60
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