Engineering Chemistry S Datta

228 ENGINEERING CHEMISTRY
Q. 28. Specific conductances decreases with dilution while the equivalent
conductance increases—explain.
Ans. When an electrolyte is diluted, degree of dissociation increases and also the total
volume increases. As a result, the number of ions per millilitre decreases. But it outweighs the
minor increase in conductance due to increase in degree of dissociation. i.e., specific conductance
decreases with dilution. But equivalent conductance increases because the total number of
ions per gram equivalent increases with dilution for the increased value of degree of dissociation.
EXERCISES
1. What is an electrolyte? Give examples. What do you mean by electrolysis?
2. (a) Explain the terms : (i) Faraday (ii) E.C.E.
(b) Relate C.E. and E.C.E.
3. (a) State the Faraday’s laws of electrolysis.
(b) Prove that E 1 E2
= = ... E Z1
Z2
Zn
n
= F.
4. (a) Define the terms:
(i) Specific conductance (ii) Equivalent conductance.
(b) Discuss the effect of change in concentration of the solution on specific conductance and
equivalent conductance.
5. (a) Define the terms (i) specific conductance and (ii) equivalent conductance. With the aid of a
plot, explain the variation of equivalent conductance of KCl and CH 3
COOH on dilution.
(b) State and explain Kohlrausch’s law of independent mobilities of ions.
6. What is meant by the transport number of an ion? How is it determined? A molar solution of
CdI 2
showed an anion transport number 1.2. How would you account for the result?
7. (a) Define the specific resistance of a solution. Mention its units.
(b) State and explain Kohlrausch’s law. Discuss its significance and applications.
8. (a) Define transport number. How will you determine transport number?
(b) Specific conductance of an electrolyte decreases, while equivalent conductance increases on
dilution—explain.
(c) State Kohlrausch’s law. Explain a few applications of this law.
9. (a) Write Kohlrausch’s empirical equation.
(b) Define specific conductance.
(c) Write the shortcomings of the theory of electrolytic dissociation.
(d) Define Faraday’s second law.
(e) Give the applications of the theory of electrolytic dissociation.
10. (a) State the relationship between the cell constant, conductivity and conductance.
(b) State Kohlrausch’s experimental equation.
(c) Define the absolute ionic mobility.
11. What is meant by equivalent conductivity of an electrolyte? Describe the method you would
adopt to measure equivalent conductivity as also its value at infinite dilution for KCl and acetic
acid.