ADDIS ABABA UNIVERSITY

Question

ADDIS ABABA INSTITUTE OF TECHNOLOGY
SCHOOL OF CHEMICAL AND BIO ENGINEERING

Applied Electrochemistry WORKSHEET -1

1. Calculate the standard potential of each of the following cells. State which one(s), if any, will proceed spontaneously as written.
a. Sn + Pb2+ Sn2+ + Pb
b. Zn+ Pb2+ Zn2+ + Pb

2. Calculate the potential of each of the following:
(a) 2 Ag(s) + Fe2+ (0.100 M) 2 Ag+ (0.100 M) + Fe(s)

3. Calculate the emf at 298 K generated by a voltaic cell in which the reaction is

Cr2O72- (aq) + 14 H+(aq) + 6 I-(aq) 2 Cr 3+ (aq) + 3 I2(s) + 7 H2O(l)

[ Cr2O72- ] = 2.0 M [H+] = 1.0 M [I-] = 1.0 M [Cr3+] = 1.0 * 10-5 M

4. The Ksp at 298 K for iron(II) fluoride is 2.4 x10-6 .
a. Write a half-reaction that gives the likely products of the two-electron reduction of FeF2(s) in water.
b. Use the Ksp value and the standard reduction potential of Fe 2+ to calculate the standard reduction potential for the half-reaction in part (a).
c. Rationalize the difference between the reduction potential in part (a) and the reduction potential for Fe 2+.

5. Can we store copper sulphate in (i)Zinc vessel (ii) Silver vessel? Give reasons.
Given E0 Cu2+/Cu = +0.34V, E0Zn2+/Zn= -0.76V) , E0Ag+/Ag = +0.80V

6. Elemental calcium is produced by the electrolysis of molten CaCl2. (a) What mass of calcium can be produced by this process if a current of 7.5 * 103A is applied for 48 h? Assume that the electrolytic cell is 68% efficient. (b)What is the minimum voltage needed to cause the electrolysis?

7. (a) How many coulombs are required to plate a layer of chromium metal 0.25 mm thick on an auto bumper with a total area of 0.32 m2 from a solution containing CrO42? The density of chromium metal is 7.20 g/cm3 . (b) What current flow is required for this electroplating if the bumper is to be plated in 10.0 s? (c) If the external source has an emf of and the electrolytic cell is 65% efficient, how much electrical power is expended to electroplate the bumper?

8. Calculate the number of kilowatt-hours of electricity required to produce 1.0 * 103 kg (1 metric ton) of aluminum by electrolysis of Al 3+ if the applied voltage is 4.50 V and the process is 45% efficient.
9.

Answer 1

Please follow the directions on the Post a New Question page (see below, too) -- indicate what YOU HAVE DONE to solve each of these. Then a chemistry tutor might help.

Homework Posting Tips

Please show your work. Tutors will not do your homework for you. Please show your work for any question that you are posting.