Q inelectrochemistry 2015
Sample questions for midterms and semi final exams
In your answer explain the meaning of all parameters you used. E.g. C =
capacitance, R = universal gas constant.
Electrochemistry of ion activity
1.Chemical potential of a 1:1electrolitegiveninterms of activities,
activitycoefficients
2.The mean activity coefficient, geometric mean.
3.Example activity: MgCl2.
4.Relationship between Ka and Km, in other words: the equilibrium constant
given in terms of activities and activity coefficients
5.Ionic strength, a definition .
6. Mean activity coefficient determination via calculation
7. Debye-Hückel extended and limiting Law
Conductivity and transportnumber
1.Base definitions: electric resistance, e. conductance, e. conductivity, e. molar
conductivity
2. The molar conductivity vs. electrolyte concentration dependence of a strong
electrolite. Use figure for explanation.
3. Strong electrolite: Kohlrausch’s law ( Λm  f (c) . Use figure for explanation.
4. Determination of limiting molar conductivity.
5. Independent migration of ions.
Electrolyte
Λm0
KCl
149.79
KI
150.31
½ K2SO4
153.48
Electrolyte
NaCl
NaI
½ Na2SO4
Λm0
126.39
126.88
130.1
Difference
23.4
23.4
23.4
Using this table explain the meaning of independent migration of ions.
6. Weak electrolites: the degree of ionization given in terms of molar
conductivities.
Λm0
7. Ostwald’s dilution law (
 f (K a )
Λm
8. Ostwald’s dilution law: determination of 0m .
9. The condition for mechanical equilibrium of transporting ion, ionic mobility.
10. The ion flux
11.  

 u  zF , explain the meaning of parameters and variables.
c
12. Transport number, a definition.
Galvanic cells
1.Anode, cathode ,liquid liquid junction – their description and working
principle.
2.Galvanic cell, electrolisyscell –the spontaneous direction of electrode
processes.
3. Cell diagram usingDaniell cell as example cell. How to make sure the
cellreaction potential to be positive?
4. Cell reaction potential, electromotive force – their definitions, conditions of
measurement Ecell.
5.The Nernst equation – the activity dependence of Ecell
6.Electrode potentials, possibility of determination of individual electrode
potentials
7. The structure of electric double layer
0
8. Eqilibrium constant determination from Ecell
data.
9. Electrolyte concentration cells: the cell diagram, the cell reaction, Nernst
equation.
10. Metal metal-ion electrode: the cell diagram, the cell reaction, Nernst
equation.
11. Metal insoluble salt electrodes: the cell diagram, the cell reaction, Nernst
equation.
12. The properties of reference electrodes.
13. Ion – ion (redox) electrode: the cell diagram, the cell reaction, Nernst
equation.
14. The hydrogen gas electrode: the cell diagram, the cell reaction, Nernst
equation.
15. The electrochemical potential scale, the standard hydrogen elctrode.
16. The electrochemical determination of pH.
17. The electrode reaction potential, formal potential
18. Temperature dependence of Ecell, EMF
Electrochemical kinetics
(This lecture is the theme of semi-final exam only)
1.The rate of reactions at phase boundary.
2. The reaction rate given in terms of current density. (diff. equation is needed)
3.Polarization, overvoltage, exchange current density.
4.Compare the current vs. polarization potential curve of an ideal polarizable
and ideal nonpolarizable electrodes. (two graphs are needed).
5. Forward and backward rate of reversible process: Fe3+ + e ↔ Fe2+ (kinetic
equation for reduction and oxidation direction).
Ex01. What molality of CuSO4 has the same ionic strength as a 1 mol/kg
molality solution of KCl?
Ex02. Calculate ionic strength for a solution that is 0.2 molal in KCl and
0.6molal in K2Cr2O7.