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Loyola College M.Sc. Chemistry Nov 2003 Electrochemistry Question Paper PDF Download

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI –600 034

M.Sc., DEGREE EXAMINATION – CHEMISTRY

 FOURTH SEMESTER – NOVEMBER 2003

CH – 4803/1020 –  ELECTRO CHEMISTRY

01-11-2003                                                                                                     Max:100 marks

1.00 – 4.00

 

PART – A                                           (10X2=20 marks)

Answer ALL questions.

 

  1. The limiting molar conductance of OHis highest among the anions – Explain.
  2. Calculate the ionic strength of a mixture containing 20 mL of 0.1M lanthanum sulphate, 30 mL of 0.5 M magnesium nitrate and 50 mL of water.
  3. In case of alkali halides the deviation from Debye Huckel Onsager equation is more marked as the atomic weight increases – Explain.
  4. Calculate the limiting molar conductance of lanthanum ion if its mobility is 7.21 x 10-8 m2 V-1 S-1.
  5. Write Lippmann’s first equation and mention its importance.
  6. Draw the plot of current density vs applied potential for an electrolytic solution and hence indicate the discharge potential of an ion.
  7. Mention the electrical properties that influence the rate of an electrochemical reaction.
  8. Bring out the differences between symmetry factor and transfer coefficient.
  9. What do you mean by non-polarisable electrode?
  10. Define exchange current density.

 

PART – B                                           (8X5=40 marks)

Answer any EIGHT questions.

 

  1. Calculate the instability constant of the complex formed in the reaction

Cu+2 + 4 NH3        [Cu (NH3)4]+2

Given Cu+2 +2  Cu(s)                                       Eo = 0.337 V

[Cu (NH3)4]2+ + 2    Cu(s)  + 4 NH3                Eo = -0.12 V.

  1. 2 M lead nitrate solution freezes at -0.05oC. Calculate its dissociation constant.  Cryoscopic constant of water is 1.86 kg K mol-1.
  2. The dissociation constant of chloroacetic acid is 1 x 10-4. Will the degree of dissociation increase or decrease if 0.1 M KCl is added to 0.1 M chloro acetic acid?
  3. Write notes on electro kinetic phenomena.
  4. Discuss electrocapillary phenomena.
  5. How is the limiting molar conductance of acetic acid determined using Debye Huckel Onsager – equation?
  6. Compare the rates of reduction of Ag+, at over voltages -0.1 and +0.1 V, which has a symmetry factor, = 0.5.
  7. Explain any one experimental method of determining the exchange current density.
  8. State Butler – volmer equation for one electron process. Derive Nernst equation from it.
  9. Determine the order of the reaction 2 H3O+ + 2e 2 H2O + H2 in acidic medium.
  10. Derive Tafel equation for cathodic process.
  11. Define half wave potential. Show that it is a constant characteristic of the electro active species.

 

 

PART – C                                           (4X10=40 marks)

Answer any FOUR questions.

 

  1. State the postulates of Debye Huckel theory and derive an expression for Debye Huckel length.
  2. Derive Debye Huckel limiting law. How is it verified?  Mention its applications.
  3. What are the features of Helmholtz Perrin model? What are its limitations?  How are these overcome in Stern’s model?
  4. a) Derive the Butler – Volmer equation for a multistep electrochemical reaction.
  5. b) Explain the condition under which the above equation reduces to simpler Butler –

Volmer equation.

  1. a) A cathodic potential of 3V is applied to Cu2+ and Na+ solutions separately.  Calculate

the over potential of the two electrodes.

  1. b) Explain any three applications of polarography.
  2. a) Obtain an expression for limiting current on the basis of concentration polarization.
  3. b) Write a note on
  4. Cyclic voltametry
  5. Amperometric titrations

 

 

 

 

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Loyola College M.Sc. Chemistry April 2006 Electrochemistry Question Paper PDF Download

             LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

LM 40

FOURTH SEMESTER – APRIL 2006

                                               CH 4805/CH 4803 – ELECTROCHEMISTRY

 

 

Date & Time : 20-04-2006/FORENOON     Dept. No.                                                       Max. : 100 Marks

 

 

 

PartA (20 Marks)

 

Answer ALL questions (10 x 2 = 20)

  1. Calculate the thickness of ionic atmosphere in 0.1M aqueous lanthanum sulphate.
  2. Compare the ion-solvent interaction of the following
    1. 1M aq KCl
    2. 1M aq Al2(SO4)3
  3. λ H+ is the highest among cations in aqueous solution. Why?
  4. How is the capacitance related to the thickness of double layer in Helmholtz Perrin

model?

  1. What are surfactants? Give example.
  2. What do you mean by a polarisable electrode? State the condition for its ideal

polarisability.

  1. What is reaction resistance? Calculate its value of an electrode having equilibrium

current density  2 .08 μA cm.

  1. Nernst equation is a special case of Butler-Volmer equation.Explain.
  2. Determine whether Cu form 0.01 M Cu2+ will be deposited or not.

( SRP :  Cu2+/ Cu = 0.34V )

  1. Obtain the relation between rate and current density of an electro-chemical reaction

from Faraday’s laws.

Part-B (40 Marks)

 

Answer any EIGHT questions (8 x 5 = 40)

  1. 11. What are electro capillary curves? What is its importance?
  2. Derive an expression for the interfacial tension applying parallel plate condenser

model.

  1. Apply Born’s model to find out the energy of ion solvent interaction.
  2. 14. Discuss the evidences for the existence of ionic atmosphere.
  3. 15. The measured emf for the cell Ag, AgBr,KBr || Hg2Br2 | Hg are 0.06839V at 25ºC

and 0.07048V at 30ºC. Write the reaction involved and calculate ∆H, ∆G and ∆S

for the reaction at 25ºC

  1. A 0.2m lead nitrate solution freezes at -0.10ºC. Calculate the dissociation constant

if Kf of water is 1.86 K molal-1

  1. Derive the Butler-Volmer equation for a one electron electrode process.
  2. 18. Define transfer coefficient. How is it determined experimentally?
  3. 19. The reversible potential and c.d of an electrode are 0.22 V and 7.2×10 -4 A cm-2

        respectively. Calculate the c.d across it   at 0.74 V if it has 40% cathodic tendency.

 

  1. 20. The tafel anodic and cathodic slopes of “applied potential vs logi ” of an

electrode process were found to be 0.04 & 0.12 respectively.  Calculate the

ransfer coefficients.

 

  1. 21. Explain the applications of Tafel equations.

 

  1. 22. The exchange current density of Pt/Fe, Feis 2.5 mA cm. Calculate the

current density across the electrode at 25C maintained at 1V when [Fe] = 0.1

M and [Fe]= 0.2 M (SRP = 0.77IV, β = 0.58)

 

Part-C (40 Marks)

 

Answer any FOUR questions (4 x 10 = 40)

 

  1. 23. Discuss sterns model of double layer structure.
  2. 24. Describe ‘Electrokinetic Phenomena’.
  3. 25. Derive Debye Huckel limiting law. How is it verified?
  4. 26. For the system Pt /Fe3+, Fe2+ at 298K the i were measured as shown below:

(mV):             50       80      100     120        150     200

(mA cm)   :  8.01  16.1    25.17    41         82.4   264

Evaluate  io and β

  1. 27. Consider the following mechanism for the deposition iron.

 

Fe2+ + H2O           FeOH+ + H+   eq const K1 ……. (1)

 

                                   FeOH+ + e            FeOH             eq const K2 ……. (2)

 

FeOH + H+ + e          Fe + H2O    eq const K3   ……. (3)

 

Derive the expression for rate if step-2 is rds

  1. Discussion of Butler -Volmer equation for different values of over potentials.

 

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Loyola College M.Sc. Chemistry April 2007 Electrochemistry Question Paper PDF Download

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

LM 52

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2007

CH 4805 / CH 4808 – ELECTROCHEMISTRY

 

 

 

Date & Time: 18/04/2007 / 9:00 – 12:00          Dept. No.                                                          Max. : 100 Marks

 

 

PART – A

 

Answer ALL the questions                                                                (10 x 2 = 20 marks)

 

  1. The deviation from Debye Huckel Onsager equation is more marked as the atomic weight of alkali metal halide increases – Explain.
  2. Which of the following will have greater ion – ion interaction?

(i) 0.01 m KCl             (ii) 0.01 m CuSO4.

  1. and  are 0.337 and 0.521V respectively. Is it easier to

oxidize  cu to cu+ or cu to cu+2?

  1. According to Stern’s model, how do ions congregate in solution?
  2. Define potential of zero charge.
  3. Derive the expression for the electrochemical reaction rate on the basis of Faraday’s laws of electrolysis.
  4. Define exchange current density of and electrode.  How is it related to its polarisability?
  5. Indicate the potential range at which an electrode shows ohmic and non ohmic behaviours.
  6. Define transfer coefficient.  How can it be determined experimentally?
  7. Define diffusion over potential.  Explain how the concentration over potential can arise mainly due to diffusion.

 

PART – B

 

Answer any EIGHT questions                                                           (8 x 5 = 40 marks)

 

  1. Consider the cell, cd/cdcl2 . 2½ H2O/Agcl(s)/Ag(s).  The emf of the cell at 15C is 0.67531and the temperature coefficient of emf is –0.00065 Vdeg-1.  Calculate DG, DS   and DH for the above cell reaction at 15oC.
  2. Derive an expression for the Debye Huckel length.
  3. Determine the solubility of BaSO4 in (i) 0.1m BaCl2 and (ii) 0.1m KNO3. Ksp of BaSO4 is 1 x 10-10 mol2 dm-6.
  4. Calculate the limiting molar conductance of lanthanum sulphate from the following data:
  1. What are electro capillary curves?  How is it influenced by surfactants?  Explain.
  2. Write notes on electro-osmosis.
  3. The exchange current density, Io of a certain electrode and its symmetry factor, b are 1.35 mA and 0.45.  Calculate is cathodic current at an over potential of 300mV.
  4. Calculate the magnitude of the anodic Tafel slope of the plot of logi vs h for an electrode having its anodic transfer coefficient 1.5 at 298K.
  5. Calculate the minimum potential required for the discharge of Ag+ from its 1x 103 M solution at 298K (The SRP of Ag+/Ag system = 0.80V).
  6. The reduction of Fe2+ to Fe follows the following mechanism

Fe2+ + H2O ⇄ FeOH+ + H+      eq conts K1 ….. (1)

FeOH + e ⇄ FeOH                eq conts K2 ….. (2)

FeOH +H+ + e ⇄ Fe + H2O      eq conts K3 ….. (3)

Determine the following parameters if step-2 is rds.

= ;       ;   n     ;  r  ;   and

  1. Discuss any five types over potential for an electrode system.
  2. State the following relation for polarography connecting
  • EMF & current density
  • Current density & concentration

Explain their applications.

PART – C

Answer any FOUR questions                                                            (4 x 10 = 40 marks)

  1. Derive Debye Huckel Onsager equation.  How is it verified?
  2. Give an account of ‘Parallel Plate Consdensor Model’ to explain the double layer structure.
  3. Define ion-ion interaction.  Derive an expression for ion-ion interaction interms of chemical potential.
  4. a) Derive the Butler-volrmer equation relating current and over potential for a

simple  electrode system.

  1. b) Deduce Ohm’s law equation from the above relation.
  1. a) Explain the factor deciding electrode rectification?
  1. b) Discuss Butler-Volmer equation for different value of over potential.
  1. The electrochemical reduction of I to I proceeds by a three step mechanism viz., fast equilibrium dissociation of (i) I to I2 & I (ii) I2 to I (iii) followed by the slow reduction of the dissociated I atoms to I.  Write the mechanism of the reaction and hence determine the transfer coefficient for the reaction.

 

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Loyola College M.Sc. Chemistry April 2008 Electrochemistry Question Paper PDF Download

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

GH 45

 

FOURTH SEMESTER – APRIL 2008

CH 4808 – ELECTROCHEMISTRY

 

 

 

Date : 21-04-08                  Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

 

PART A

Answer ALL questions                                                                (10 x 2 = 20 Marks)

 

  1. Calculate the thickness of the ionic atmosphere in 0.10M aqueous solution of

barium chloride at 298K. (Dielectric constant of H2O at 298K = 78.6).

  1. Derive the expression for the rate of an electrode reaction using Faraday’s law.
  2. An electrolyte of the type A2B3 is 85% ionized in 0.01M solution.

What is the value of Vant’ Hoff  i factor?

  1. What is Wien effect?
  2. Write Lipmann equation and explain the terms.
  3. What are the factors which affect the symmetry factor in an electrode reaction?
  4. Explain the various factors which influence the zeta potential.
  5. What is meant by stoichiometric number?
  6. Removal of oxygen from analyte is very essential in polarographic analysis.Why?
  7. Write the expression for the charge transfer resistance in an electrode reaction

at low overpotential.

 

PART B

 

Answer any EIGHT questions                                                         (8 x 5 = 40 Marks)

 

  1. Discuss the Born model for ion- solvent interactions.
  2. Account for the abnormal conductance of H3O+ ion in protic solvents.
  3. Explain the electrokinetic phenomena on the basis of irreversible thermodynamics.
  4. Calculate the values of Debye Huckel Onsager constants A and B for methanol

at 298K. (For methanol  ε =31.5 and  η = 0.545 centipoise).

  1. Distinguish between polarisable and non-polarisable electrodes with

suitable examples.

  1. Discuss the mechanism of electro-reduction of nitrobenzene.
  2. Explain how electrophoretic and relaxation effects affect the mobility of

an ion in solution.

  1. What are the advantages of DME? Mention two of its disadvantages.
  2. What is zeta potential? How is it determined?
  3. Deduce Nernst equation from Butler – Volmer equation.
  4. Explain: Half-wave potential and Residual current
  5. Calculate the mean ionic activity co-efficient in 0.01M aqueous solution of

potassium ferrocyanide at 298K using Debye – Huckel limiting law.

 

 

 

 

 

 

PART C

 

Answer any FOUR questions                                               (4 x 10 = 40 Marks)

 

  1. Derive Debye Huckel Onsager equation. How is it verified?

What are its limitations?

  1. Discuss the Stern model of double layer structure.

How is it superior to other models?

25     a).Derive Butler – Volmer equation for a single step one electron transfer reaction.

  1. b) Discuss the high field and low field approximations of the above equation.
  2. a)Describe any two applications of polarography.

b)Calculate the maximum diffusion current in the polarographic reduction of Zn+2

ions from a 3 x 10-3 M solution with diffusion co-efficient of 7.2 x 10-6 cm2 s-1.

The capillary used in DME is such that it liberates 1.5 mg of Hg per second

with a drop time of 2 seconds.

  1. Discuss the use of Pourbaix diagram in understanding the thermodynamic stability

of iron at different pH values.

28     a).A 0.2m solution of lead nitrate freezes at -0.10o C If Kf  of water is 1.86 Kmolal-1

          what is the degree of dissociation of lead nitrate in 0.20m solution?

b)Consider the following  mechanism for the reduction of I3 –   ion

 

Step 1                 I3–       I2    +    I

Step 2                 I2     ­    2 I

 

Step 3                 2 (I  +  e–     →    I )

 

 

Derive the rate equation for the reaction considering step 3 as the rate determining

step and explain how the electrochemical- reaction orders establish the mechanism.

 

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Loyola College M.Sc. Chemistry April 2008 Electrochemistry Question Paper PDF Download

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

GH 59

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2008

    CH 4805 / 1020 – ELECTROCHEMISTRY

 

 

 

Date : 03/05/2008            Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

PART A

Answer ALL questions                                                                      (10 ´ 2 = 20 Marks)

 

  1. Calculate the ionic strength in 0.01M potassium ferricyanide solution.
  2. Explain the significance of symmetry factor in an electrode reaction.
  3. How does electrophoretic effect affects the ionic mobility in a solution of strong electrolyte?
  4. Explain IHP and OHP at the electrode – electrolyte interface.
  5. What is meant by Lippmann potential?
  6. Explain concentration polarization.
  7. Vant Hoff ‘ i ‘ factor for AB2 type electrolyte at a given concentration is 2.8. What is its percentage of ionization?
  8. Illustrate primary cell with an example.
  9. The solubility of mercurous chloride in water at 25o C is 1.0 x 10-5 mol dm-3 . What is its KSP value at the same temperature?
  10. What are surfactants? Give an example.

PART B

Answer any EIGHT questions                                             (8 x 5 = 40 Marks)

 

11  State Debye – Huckel limiting law. How is verified?What is its limitation?

  1. Account for the abnormal mobilities of H3O+ and OH ions in aqueous solution.
  2. How is the solubility product of a sparingly soluble salt like AgCl is determined from EMF measurements?
  3. Deduce Nernst equation from Butler – Volmer equation.
  4. Write briefly on Helmholtz – Perrin model for an electrical double layer.
  5. Distinguish between polarisable and non-polarisable electrodes with suitable examples.
  6. Explain the dependence of pH on corrosion using Pourbaix diagram.
  7. Write briefly on (i)Streaming potential (ii)Sedimentation potential
  8. Calculate the thickness of ionic atmosphere in 0.10M calcium chloride solution in water at 27o C . (Dielectric constant of water is 78.6)
  9. Write a note on H2 – O2 fuel cell.
  10. Explain Debye Falkenhagen effect.

PART C

Answer any FOUR questions                                              ( 4 x 10 = 40 Marks)

 

  1. Derive Butler – Volmer equation for a single step single electron transfer reaction and explain the low and high field approximations.
  2. Discuss the Stern model for the electrode – electrolyte interface.
  3. Derive the Debye – Huckel – Onsager equation .
  4. a)Explain the amperometric method of estimation of silver nitrate.

b)What are electrocpillary curves?Explain its significance.

  1. a)How does hydrogen over voltage arise?

b)Describe any two methods employed for the prevention of corrosion.

27.a)The equilibrium exchange current density for the reaction

H+  +  e   →     H2

on nickel  at 25o C is 1.00 x 10-5  A cm-2 . What current density would be

necessary to attain a cverpotential of 0.1V ? (α = 0.5).

b)For Weston standard cell at 298K emf is 1.01032 V and temperature

co-efficient of  emf of the cell is -5.00 x 10-5  VK-1  . Calculate ∆ G , ∆H

and  ∆ S of the cell reaction.

 

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Loyola College M.Sc. Chemistry April 2009 Electrochemistry Question Paper PDF Download

        LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

WD 47

FOURTH SEMESTER – April 2009

CH 4808 / 4805 / 4803 – ELECTROCHEMISTRY

 

 

 

Date & Time: 21/04/2009 / 9:00 – 12:00  Dept. No.                                                     Max. : 100 Marks

 

 

PartA (20 Marks)

Answer ALL questions (10 x 2 = 20)

  1. Calculate the ionic strength of a solution obtained by mixing 50 ml of 0.02 M
    Na2SO4 and 50 ml of 0.02 M cerium (III) sulphate solutions.
  2. Mention the factors affecting the thickness of the ionic atmosphere of an electrolytic solution.
  3. E°red of Au+/Au is 1.68 V, E°red Au3+/Au is 1.50 V. Calculate E°oxi  of Au+/Au3+
    at 25°
  4. Calculate the zeta potential of a colloidal particle in aqueous solution that has an
    electrophoretic mobility of 1.1   10-8 m2 s-1 V-1.  The coefficient of viscosity of water  is 8.91 x 10-4 kg m-1 s-1 and  Î = 78.3.
  5. What is ‘Dorn Effect’?
  6. Draw the general pattern of the plot of current density vs overvoltage for an electrode having symmetry factor 0.75.
  7. What do you mean by the high field approximation of the Butler-Volmer equation.
  8. The diffusion current of a certain metal ion at  3 × 10-2 mM is 3.3µA calculate its diffusion current at 6.9 × 10-2 mM concentration.
  9. Bring out the difference between voltammetry and polarography.
  10. Differentiate between half wave and standard reduction potentials.

Part-B (40 Marks)

Answer ANY EIGHT questions (8 x 5 = 40)

  1. Deduce Lippmann’s equation and mention its significance.
  2. Explain the influence of electrolytes on electrokinetic effects.
  3. The thermodynamic dissociation constant of a weak acid (HA) at 25°C is 2 10-5.
    What is the degree of dissociation of 0.1 M acid in 0.01 M KNO3 (aq) solution?
  4. Calculate Kh for NH4Cl if the EMF of the cell.

Pt½H2(1 atm)½NH4Cl(0.2M) ½½ KCl(1M)½Hg2Cl2½Hg

at 25° C is 0.574 V and E°red of calomel electrode is 0.28 V.

  1. Determine the potential due to ionic atmosphere around cation at 25° C for
    10-3M CaCl2(aq)  if Î0 = 8.854  ´ 10-12 C2J-1m-1 and dielectric constant of water is
    3.
  2. Explain Wien’s effect and its importance in the study of strong electrolytes.
  3. Electrolysis of a solution of Cu2+ produces 16 mg of Cu in 2 minutes. Calculate the rate of the reaction.

 

  1. What do you mean by non polarisable electrode? How is it related to its current density?
  2. Calculate the current density across an electrode (β = 0.45) at an applied potential of 0.23V if its equilibrium potential is 0.09V
  3. Explain migration and diffusion currents. Which current is significant in poloragraphy? How is it achieved?
  4. The dissolution of iron follows the following mechanism:

Fe  +  H2O         FeOH      +  H+ +   e ;  Eq Const K1……….……1

FeOH                  FeOH+    +   e–                ;   Eq Const K2……….…….2

FeOH+   + H+       Fe2+  + H2O              ;  Eq Const K3 …………….3

Determine its transfer coefficients if step-2 is the rate determining step.

  1. Explain the electrochemical reduction of a typical aromatic ketone.

Part-C (40 Marks)

Answer ANY FOUR questions (4 x 10 = 40)

  1. What is the need for a model on electrical double layer? Explain Helmohlltz-Perrin model and mention its defects.                                         (3 + 5 + 2)
  2. (a) Mention the assumptions of Debye-Huckel theory and explain any one
    application of Debye-Huckel limiting law equation.                  (3 + 4)

(b) What is the need to modify the limiting law equation.            (3)

  1. Explain any two of the following:
  • Relaxation effect
  • Electroosmosis
  • Gouy-Chap mann model of electrical double layer
  • van’t Hoff factor.
  1. Derive the relation between current density and applied potential for an electrode undergoing multistep multi electron reaction
  2. Define limiting current. Derive an expression for it relating to concentration on the basis of the concept of concentration polarization.
  3. Explain the following with suitable examples and figures.
  • Amperometric titrations
  • Electrodes as anodic rectifiers
  • Three electrode system.

 

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Loyola College M.Sc. Chemistry April 2012 Electrochemistry Question Paper PDF Download

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

M.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2012

CH 4808 – ELECTROCHEMISTRY

 

 

Date : 16-04-2012             Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

 

PART – A

Answer ALL questions                                                                                      (10 x 2 = 20 marks)

  1. Mention the factors that favour ion association in an electrolytic solution.
  2. Determine the mean activity coefficient of 10-3 m La(NO3)3 in water using

Debye – Huckellimitting law at 25oC.

  1. Calculate the work of charging Li+ in vacuum. The radius of Li+ is 59 pm

0 = 1.112 x 10-10 C2 J-1 m-1).

  1. Mention the evidences for the existence of ionic atmosphere around an ion of an electrolyte.
  2. What is zeta potential?
  1. What is voltametry? How does it differ from potentiometry?
  2. The Butler-Volmer equation under certain condition(s) can be expressed in the form: i = A Sinh(kη). Express the values of A and k in terms of the corresponding physical constants?
  3. Explain the condition under which an electrode will (i) show ohmic behavior (ii) act as a rectifier.
  4. Define stoichiometric number. How can it be determined experimentally?
  5. Explain concentration polarization. What are the factors contributing to it?

 

PART – B

Answer any EIGHT questions                                                                     (8 x 5 = 40 marks)

  1. For the cell, Zn + 2 AgCl(s)® 2 Ag + Zn2+ + 2Cl.Eo cell at 298 K is 1.034 V. Evaluate DGo, DHo and DSo for the cell if the temperature coefficient of EMF is -54 x 10-4 V/K.
  2. Calculate the thickness of the ionic atmosphere in 0.1 M KCl at 298 K in

nitro benzene (Î = 34.8).  (Îo = 8.85 x 10-12 C2J-1 m-1).

 

  1. Differentiate chemical potential and electrochemical potential and deduce the relevant equations.
  2. Discuss the salient features of Helmholtz – Perrin model of electrical double layer.
  3. How is Debye- Huckel – Onsagar equation verified experimentally?
  4. Calculate the molar conductivity of NaI in acetone.  The viscosity of acetone is 3.16 milli poise.  The radii of Na+and I ions are 260 and 300 pm respectively. (1 poise = 10-7 ohm C2 om-3).
  5. The cathodic symmetry factor, β of an electrode is less than 0.5. Draw the following curves in a plot of current density vs applied potential:

(i) Anodic current density, ia (ii) Cathodic current density, ic

(iii) Net current density, i

  1. The current density of an electrode for an over potential 10 mV was found to be 0.62mAcm-2.  What will be the current density when the over potential applied is 100 mV, if its  cathodic  symmetry factor is 0.56.
  2. Calculate the minimum potential required for the discharge of Cu2+ from its 5×10-3M solution at 298K (SRP of Cu2+/ Cu = 0.34V).
  3. The reduction of Fe2+ to Fe follows the following mechanism:

Fe2+ + H2O            FeOH+ + H+           eqconts K1…….(1) Fast

FeOH++ e          FeOH           eq conts K2……. (2) Fast

FeOH + H+ + e          Fe +H2O         eq conts K3…….(3) Slow

Write the expression for the current density of the rate determining step and step-2.

  1. Derive the relation between applied potential and current density for a cathodic reaction on a mercury surface.
  2. Define residual, diffusion and limiting currents. How do they arise and how are they related to each other?

PART – C

Answer any FOUR questions                                                                   (4 x 10 = 40 marks)

  1.  a) Mention the assumptions of Debye – Huckel theory of activity coefficients.
  1. b) Derive linearised Poisson – Boltzmann equation and mention its

significance.

 

 

  1. Explain any two of the following
  1. a) Electrocapillarity b) Grotthus type conduction
  2. c) Electrokinetic phenomena d) Diverse ion effect.
  1. a) Discuss the theoretical basis for Debye – Huckel – Onsager equation.
  1. b) How is solvation number determined?
  1. (a) Derive the relation between current and over potential for a simple

one electron electrode system.

(b) Deduce Nernst equation from the above relation.

  1. (a) What do you mean by electrode rectification?

(b)  Discuss Butler-Volmer equation for different symmetry factors,

β (<0.5 , 0 &>0.5)

  1. The evolution of hydrogen on a metal surface follows a two-step  mechanism, viz., a fast  equilibrium discharge of H3O+ followed by the slow chemical desorption of the adsorbed H atoms. Write the mechanism of the reaction and hence determine the order and the transfer coefficient for the discharge process.

 

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“Loyola College B.Sc. Chemistry April 2008 Electrochemistry Question Paper PDF Download”

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – CHEMISTRY

GH 15

 

FOURTH SEMESTER – APRIL 2008

CH 4502 – ELECTROCHEMISTRY

 

 

 

Date : 26/04/2008                Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

PART – A

 

Answer ALL the questions                                                                            (10 x 2 = 20 marks)

 

  1. Write down the reactions taking place at the anode and cathode separately

Cu½ Cu2+ ½½ Ag+ ½ Ag

  1. What is meant by primary reference electrode?
  2. What is LJP?  How can it be minimized?
  3. Explain why quinhydrone electrode cannot be used for alkaline solution.
  4. Calculate the ionic strength of 0.01 M Cu SO4 solution.
  5. Compare the transference numbers of chloride ion in HCl and NaCl.
  6. Mention any two advantages of conductometric titrations.
  7. What is meant by activity of an electrolyte?  How is it related to activity coefficient of an electrolyte?
  8. Define overvoltage.
  9. What is concentration polarization?

 

PART – B

 

Answer any EIGHT questions                                                                 (8 x 5 = 40 marks)

 

  1. Describe the following types of electrodes with examples and write the electrode reactions.      a) Metal – Metal ion electrode  b) gas electrode.

 

  1. Describe the construction and working of a calomel electrode.

 

  1. How will you determine the standard electrode potential of zinc electrode?

 

  1. The standard oxidation potentials of Ce3+– Ce4+ and Fe2+– Fe3+ systems are – 1.61 and

-0.771 respectively.  Calculate the equilibrium constant at 25oC for the reversible process     Fe2+ + Ce4+  Ce3+ + Fe3+.

  1. Describe any one method of determination of pH of a solution by EMF measurement.

 

  1. Derive expressions for DG, DH and DS in terms of EMF of a cell.

 

  1. Differentiate between a strong and a weak electrolyte from the variation of conductance with concentration.

 

  1. Calculate the equivalent conductance at infinite dilution of NH4OH, if the equivalent conductance at infinite dilution of Ba(OH)2, BaCl2 and NH4Cl are 228.8, 120.3 and 129.8 ohm-1 cm2 eqiv—1 respectively.

 

  1. How is Ka of a weak acid determined by conductance measurement?

 

  1. Discus the conductometric titrations of a) a strong acid with a strong base b) a strong acid with a weak base.

 

  1. What are the applications of overvoltage?

 

  1. How is the decomposition voltage in an aqueous solution measured?

 

 

PART – C

 

Answer any FOUR questions                                                                        (4 x 10 = 40 marks)

 

  1. Define EMF.  How is solubility product of a sparingly soluble salt determined from EMF measurement?
  2. What is a standard cell?  Discuss the working of Weston standard cell.
  3. What are concentration cells? Derive an expression for the EMF of an electrolyte concentration cell without transference.
  4. The cell Cd½Cd Cl2 ½½ Ag Cl ½ Ag  has an emf of 0.675 V at 25oC and the temperature coefficient of emf is – 0.00065 V deg-1.  Calculate DG, DH and DS for the cell reaction.
  5. What is meant by transference number of an ion?  Describe the moving boundary method for the determination of transference number of an ion.
  6. a)  Give a account of Debye – Huckel theory of strong electrolytes.                         (6)
  1. b) Discuss the principle of polarography. (4)

 

 

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“Loyola College B.Sc. Chemistry April 2009 Electrochemistry Question Paper PDF Download”

       LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

WD 14

B.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – April 2009

CH 4502 – ELECTROCHEMISTRY

 

 

 

Date & Time: 24/04/2009 / 9:00 – 12:00  Dept. No.                                                   Max. : 100 Marks

 

 

                                                                      PART – A                   

Answer ALL questions.                                  (10 x 2 = 20 marks)

 

  1. Define electromotive series. Give its application.
  2. What is a reversible cell?
  3. What is LJP? How can it be minimised?
  4. What are Fuel cells? Give its application.
  5. State Faraday’s first law of electrolysis.
  6. Distinguish between Strong and Weak electrolyte.
  7. Define the term activity of an electrolyte.
  8. Explain the principle involved in the conductometic titration of AgNO3.
  9. Define the term limiting current.
  10. Define Overvoltage.

 

PART – B

Answer any EIGHT questions.                                   (8 x 5 = 40 marks)

 

  1. Explain the following with an example.

(i)         Metal – Metal ion electrode.

(ii)        Amalgam electrode.

  1. Describe the construction and working of Weston cell.
  2. Calculate the EMF of the concentration cell

Pt;  H2(P1),  HCl,  H2(P2);  Pt at 25oC.

If P1 = 600 torr and P2 = 400 torr.

  1. How will you determine the standard electrode potential of copper electrode.
  2. How will you determine the pH of a solution using glass electrode.
  3. Derive expressions for ΔG; ΔH  and  ΔS  in terms of EMF of a cell.
  4. How is transport number determined by moving boundary method?
  5. Calculate the equivalent and molar conductivities of 0.08N H2SO4  solution

having specific conductivity  1.72 x 10-3  Scm-1.

  1. How is Kb of a weak base determined by conductance measurement?
  2. Discuss the principle and procedure for conductometric titration of a

Strong acid with a strong base.

  1. Discuss on the applications of decomposition potential.
  2. Explain the electrochemical theory of corrosion.

 

                                                                      PART – C

Answer ANY FOUR questions.                                 (4 x 10 = 40 marks)

 

  1. How is solubility of sparingly soluble salt determined by EMF measurements.
  2. (i) Derive the Nernst electrochemical equation.

(ii)        Calculate the reduction potential of the electrode

Pt/Cl2(g)  (1.15)atm/2Cl (0.01M).

Given that EoCl2/2Cl = 1.8V.

  1. What are concentration cells? Derive an expression for the EMF of an electrolyte  for a concentration cell without transference.
  2. Explain any four applications of EMF.
  3. (i) Discuss the Arrhenius theory of electrolytic dissociation.

Give its limitations.

  • Explain the principle involved in the potentiometric titrations.
  1. (i) Discuss on the Debye-Huckel theory of strong electrolytes.

(ii)        Explain the principle of polarography.

 

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“Loyola College B.Sc. Chemistry April 2011 Electrochemistry Question Paper PDF Download”

LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

B.Sc. DEGREE EXAMINATION – CHEMISTRY

FOURTH SEMESTER – APRIL 2011

CH 4502 – ELECTROCHEMISTRY

 

 

Date : 07-04-2011              Dept. No.                                        Max. : 100 Marks

Time : 1:00 – 4:00

 

PART – A

Answer ALL questions.                                                                                          (10 x 2 = 20 marks)

 

  1. Define electromotive force.
  2. What is a reversible cell.
  3. Write the relationship between ΔG and  EMF.
  4. What are fuel cells? Give its application.
  5. State Faraday’s law of electrolysis.
  6. Define ionic mobility.
  7. What is cell constant?
  8. Define Solubility Product.
  9. What is meant by decomposition potential.
  10. Write down the Ilkovic equation and mention the terms involved in it.

 

PART – B

Answer any EIGHT questions.                                                                                (8 x 5 = 40 marks)

  1. What is meant by single electrode potential? How could you measure the single electrode potential?
  2. Describe the construction and working of Weston cell.
  3. What is the potential of a half-cell consisting of zinc electrode in 0.01M ZnSO4 solution at

25oC, Eored = -0.763 V.

  1. Explain liquid junction potential. How does it affect EMF measurements?
  2. Derive Nernst equation for electrode potentials.
  3. Explain redox potentiometric  titration with an example.
  4. A solution of silver nitrate containing 12.14 g of silver in 50 ml of solution was

electrolysed between platinum electrodes.  After electrolysis, 50 ml of the anode solution was found

to contain 11.55 g of silver, while 1.25 g of metallic silver was deposited on  the cathode.  Calculate

the transport number of Ag+ and NO3¯   ions.

  1. How the Dc of an electrolyte solution can be determined.
  2. How could you determine the solubility of a sparingly soluble salt by conductivity

measurements.

  1. Discuss on the Debye Huckel theory of strong electrolytes.
  2. Describe how the electrolytic separations of metals are carried out.
  3. Explain the principle of polarography.

 

PART – C

Answer any  FOUR  questions.                                                                               (4 x 10 = 40 marks)

 

  1. Explain the following :

(i)    Redox electrode              (ii)   Saturated calomel electrode

  1. Explain any four applications of EMF.
  2. How the pH of a solution can be determined using quinhydrone electrode.
  3. What are concentration cells? Derive an expression for the EMF of a concentration cell with

transference.

  1. (i) Discuss Arrhenius theory of electrolytic dissociation. Give its limitations.

(ii)   Explain the variation of specific and equivalent conductance with concentration.

  1. (i) Explain the electrochemical theory of corrosion.

(ii)   Discuss the principle and procedure for conductivity  titration of a weak acid with a strong  base.

 

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