Unit 4: Electrochemistry - Practice Quiz

CHE124 — Engineering Chemistry 60 Questions
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1 The cell constant of a conductivity cell is defined as the ratio of the distance between the electrodes to their area of cross-section, expressed as:

Cell constant determination Easy
A.
B.
C.
D.

2 The unit of cell constant is:

Cell constant determination Easy
A.
B.
C.
D.

3 Cell constant is obtained by multiplying the observed conductance by which quantity?

Cell constant determination Easy
A. Molar mass
B. Resistivity
C. Normality
D. Temperature

4 The SI-based common unit of specific conductance (conductivity) is:

Specific and Molar conductance (numericals) Easy
A.
B.
C.
D.

5 If the specific conductance of a solution is and its molar concentration is , the molar conductance is:

Specific and Molar conductance (numericals) Easy
A.
B.
C.
D.

6 Molar conductance is related to specific conductance and molar concentration (in ) by:

Specific and Molar conductance (numericals) Easy
A.
B.
C.
D.

7 A substance that conducts electricity in molten or aqueous state by producing ions is called:

Introduction to electrolytes Easy
A. A dielectric
B. An electrolyte
C. A semiconductor
D. An insulator

8 Which of the following is a strong electrolyte?

Introduction to electrolytes Easy
A.
B.
C.
D.

9 In an electrochemical cell, conduction of current within the electrolyte solution occurs through the movement of:

electrochemical cells and cell conductance Easy
A. Ions
B. Neutral molecules
C. Free electrons
D. Photons

10 In a galvanic cell, chemical energy is converted into:

Electrolytic and galvanic cells Easy
A. Electrical energy
B. Mechanical energy
C. Heat energy only
D. Light energy

11 In an electrolytic cell, the reaction occurring is:

Electrolytic and galvanic cells Easy
A. Spontaneous, producing electricity
B. Purely thermal
C. Non-spontaneous, driven by external electricity
D. Always at equilibrium

12 In a galvanic cell, oxidation takes place at the:

Electrolytic and galvanic cells Easy
A. Voltmeter
B. Salt bridge
C. Cathode
D. Anode

13 In the electrochemical series, elements are arranged according to their:

electrochemical series Easy
A. Atomic mass
B. Standard electrode potential
C. Melting point
D. Density

14 A metal placed higher in the activity/electrochemical series (more negative ) tends to act as a:

electrochemical series Easy
A. Stronger oxidizing agent
B. Neutral element
C. Better electrical insulator
D. Stronger reducing agent

15 The EMF of a galvanic cell is calculated as:

cell emf measurement Easy
A.
B.
C.
D.

16 The instrument commonly used for accurate measurement of cell EMF without drawing current is the:

cell emf measurement Easy
A. Potentiometer
B. Ohmmeter
C. Ammeter
D. Galvanometer alone

17 The Nernst equation for a cell reaction at 298 K is written as:

Nernst equation and numerical problems Easy
A.
B.
C.
D.

18 For the electrode at 298 K, the value of used in the Nernst equation is:

Nernst equation and numerical problems Easy
A.
B.
C.
D.

19 The relationship between the standard Gibbs free energy change and standard cell EMF is:

Thermodynamic overview of Electrochemical processes Easy
A.
B.
C.
D.

20 The electrical double layer (HDL) that gives rise to single electrode potential forms at the interface between:

Single electrode potentials (origin and HDL) Easy
A. Two gas bubbles
B. The metal electrode and the solution
C. Two different metals
D. The wire and the voltmeter

21 A conductivity cell filled with KCl (specific conductance ) shows a resistance of . What is the cell constant?

Cell constant determination Medium
A.
B.
C.
D.

22 The cell constant of a conductivity cell is defined as:

Cell constant determination Medium
A. (area / distance)
B.
C. (distance area)
D. (distance between electrodes / area of cross-section)

23 A solution has specific conductance and concentration . What is its molar conductance?

Specific and Molar conductance (numericals) Medium
A.
B.
C.
D.

24 The resistance of a solution is in a cell with cell constant . What is the molar conductance?

Specific and Molar conductance (numericals) Medium
A.
B.
C.
D.

25 How does molar conductance of a strong electrolyte vary with dilution?

Specific and Molar conductance (numericals) Medium
A. It increases sharply toward infinity
B. It decreases sharply with dilution
C. It increases slightly with dilution
D. It remains completely constant

26 Which of the following is a weak electrolyte?

Introduction to electrolytes Medium
A.
B.
C.
D.

27 According to Kohlrausch's law, the limiting molar conductivity of an electrolyte is:

Introduction to electrolytes Medium
A. The sum of individual limiting ionic conductivities
B. The product of ionic conductivities
C. The difference of cation and anion conductivities
D. Independent of the nature of the ions

28 The conductance of an electrolytic solution is related to resistance as:

electrochemical cells and cell conductance Medium
A.
B.
C.
D.

29 In a galvanic cell, oxidation occurs at the anode which is designated as:

Electrolytic and galvanic cells Medium
A. Positive electrode
B. Reference electrode
C. Neutral electrode
D. Negative electrode

30 Which statement correctly distinguishes an electrolytic cell from a galvanic cell?

Electrolytic and galvanic cells Medium
A. An electrolytic cell converts electrical energy into chemical energy
B. In an electrolytic cell no external power is required
C. In an electrolytic cell the reaction is spontaneous
D. An electrolytic cell converts chemical energy into electrical energy

31 Based on the electrochemical series, which metal is the strongest reducing agent?

electrochemical series Medium
A.
B.
C.
D.

32 A metal can displace another metal from its salt solution if the displacing metal has a:

electrochemical series Medium
A. Zero reduction potential
B. Equal reduction potential
C. Higher (more positive) reduction potential
D. Lower (more negative) reduction potential

33 The standard EMF of the cell given and is:

cell emf measurement Medium
A.
B.
C.
D.

34 The EMF of a cell is best measured using a potentiometer rather than a voltmeter because:

cell emf measurement Medium
A. It short-circuits the cell during measurement
B. It draws negligible current, giving true reversible EMF
C. It heats the cell for accurate readings
D. It draws maximum current from the cell

35 For the electrode at , the Nernst equation is:

Nernst equation and numerical problems Medium
A.
B.
C.
D.

36 The electrode potential of a hydrogen electrode at (with ) at is:

Nernst equation and numerical problems Medium
A.
B.
C.
D.

37 For the Daniell cell at , if , the cell EMF equals:

Nernst equation and numerical problems Medium
A.
B. Half of
C.
D.

38 The relationship between standard cell EMF and standard Gibbs free energy change is:

Thermodynamic overview of Electrochemical processes Medium
A.
B.
C.
D.

39 For a cell with and , the standard free energy change () is approximately:

Thermodynamic overview of Electrochemical processes Medium
A.
B.
C.
D.

40 The Helmholtz Double Layer (HDL) at a metal-solution interface arises due to:

Single electrode potentials (origin and HDL) Medium
A. Separation of charges forming oppositely charged layers at the interface
B. Evaporation of the solvent from the electrode
C. Complete mixing of ions with the metal lattice
D. Uniform charge distribution throughout the solution

41 A conductivity cell filled with KCl (specific conductance ) shows a resistance of . When filled with an unknown electrolyte, the resistance is . What is the specific conductance of the unknown solution?

Cell constant determination Hard
A.
B.
C.
D.

42 The molar conductance of acetic acid is and . Calculate the dissociation constant .

Specific and Molar conductance (numericals) Hard
A.
B.
C.
D.

43 For the cell with , the cell EMF at is:

Nernst equation and numerical problems Hard
A.
B.
C.
D.

44 A cell has and for a 2-electron reaction. The entropy change at is (F = 96500 C):

Thermodynamic overview of Electrochemical processes Hard
A.
B.
C.
D.

45 Using standard reduction potentials , , , which species can oxidize spontaneously?

Electrochemical series Hard
A. Neither nor
B. only
C. Both and
D. only

46 The EMF of the concentration cell is at . The ratio is:

Nernst equation and numerical problems Hard
A.
B.
C.
D.

47 For a cell reaction with and at , the equilibrium constant is approximately:

Nernst equation and numerical problems Hard
A.
B.
C.
D.

48 The resistance of a solution in a cell of cell constant is . The molar conductance in is:

Specific and Molar conductance (numericals) Hard
A.
B.
C.
D.

49 The electrical double layer (Helmholtz double layer) at a metal-solution interface primarily gives rise to:

Single electrode potentials (origin and HDL) Hard
A. The bulk conductivity of the electrolyte solution
B. The junction potential between two half-cells
C. A potential difference across the interface constituting the electrode potential
D. The ohmic resistance of the metal electrode

50 Which condition must be satisfied for an electrochemical cell to be thermodynamically reversible?

Reversible and irreversible cells Hard
A. An external EMF exactly equal and opposite to cell EMF gives zero net current
B. The cell delivers maximum current through a short circuit
C. The cell reaction is spontaneous in only one direction
D. The electrode reactions proceed at a fixed high current density

51 In an electrolytic cell used for electroplating, the correct assignment of electrode signs and processes is:

Electrolytic and galvanic cells Hard
A. Cathode is positive and oxidation occurs there
B. Anode is negative and reduction occurs there
C. Anode is negative and oxidation occurs there
D. Cathode is negative and reduction occurs there

52 A potentiometer is preferred over a voltmeter for measuring cell EMF because:

cell emf measurement Hard
A. It draws a large current to give a stable reading
B. It measures EMF at zero current, avoiding IR drop within the cell
C. It measures only the electrode potential of the cathode
D. It heats the cell to maintain thermodynamic equilibrium

53 For the half-cell , . Keeping all other concentrations at unity, the electrode potential when (at ) is:

Nernst equation and numerical problems Hard
A.
B.
C.
D.

54 For a galvanic cell, . If and , the enthalpy change is:

Thermodynamic overview of Electrochemical processes Hard
A.
B.
C.
D.

55 The molar conductance of a strong electrolyte increases slightly with dilution, whereas that of a weak electrolyte increases sharply. The best explanation is:

Introduction to electrolytes Hard
A. Strong electrolytes are fully ionized so only inter-ionic effects lessen, while weak electrolytes ionize more on dilution
B. Both electrolytes ionize completely, but ion mobility differs greatly
C. Weak electrolytes precipitate on dilution, reducing resistance
D. Strong electrolytes dissociate further while weak ones associate on dilution

56 The limiting molar conductance of can be obtained from of , , and using Kohlrausch's law as:

electrochemical cells and cell conductance Hard
A.
B.
C.
D.

57 For the cell , and measured at . The pH of the anode solution is:

Nernst equation and numerical problems Hard
A.
B.
C.
D.

58 The cell constant of a conductivity cell has SI units of because it equals:

Cell constant determination Hard
A. The ratio of electrode separation to electrode area ()
B. The ratio of area to separation ()
C. The product of resistance and specific conductance
D. The product of electrode area and separation ()

59 The Daniell cell operating with a finite current is best classified as behaving:

Reversible and irreversible cells Hard
A. Irreversibly, since finite current produces IR drop and polarization
B. Reversibly, since the reaction can be reversed at any current
C. Irreversibly, only if the electrolytes are mixed
D. Reversibly, because both electrodes are metallic

60 During electrolysis of molten , a current of is passed for . The mass of Na deposited at the cathode is (Na = 23, F = 96500 C):

Electrolytic and galvanic cells Hard
A.
B.
C.
D.