Electrode Potential and Standard Electrode Potential - UNSOLVED PRACTICE SET

Q7. Define standard electrode potential. Why is the standard hydrogen electrode (SHE) used as a reference electrode?

Q8. Arrange the following metals in order of increasing tendency to lose electrons: Cu, Zn, Mg, Ag. [Given: E°(Cu²⁺/Cu) = +0.34 V, E°(Zn²⁺/Zn) = -0.76 V, E°(Mg²⁺/Mg) = -2.37 V, E°(Ag⁺/Ag) = +0.80 V]

Q9. Why is it not possible to measure the absolute electrode potential of a single half-cell?

Q10. What is a reference electrode? Name two commonly used reference electrodes other than SHE and give their standard potentials.

Q11. Your school lab has a piece of iron and a piece of copper. Based on their standard electrode potentials, predict which metal will corrode when both are exposed to moist air and explain why.

Q12. Why is the standard hydrogen electrode (SHE) called a reversible electrode? What are the practical difficulties in using SHE?

Q13. Discuss electrode potential and standard electrode potential in detail:

(a) Definition of electrode potential and its origin

(b) Standard conditions for measuring standard electrode potential

(c) The standard hydrogen electrode (SHE) — construction, working, and why E° = 0 V

(d) Sign convention — IUPAC convention for electrode potentials

(e) Difference between reduction potential and oxidation potential

(f) Measurement of standard electrode potential using SHE

Q14. Explain the factors affecting electrode potential:

(a) Nature of the metal — ionisation enthalpy, sublimation enthalpy, hydration enthalpy

(b) Concentration of ions — Nernst equation relationship

(c) Temperature

(d) Pressure (for gas electrodes)

(e) Why some metals have positive E° values while others have negative E° values

Illustrate with examples of alkali metals, alkaline earth metals, and transition metals.

Q15. Standard electrode potentials guide countless applications in India. Discuss:

(a) How E° values help predict the feasibility of extracting metals from ores (e.g., why aluminium is extracted by electrolysis while copper by smelting)

(b) Why zinc coating (galvanisation) protects iron structures across India

(c) The use of electrode potential data in designing sacrificial anodes for protecting ship hulls and offshore oil platforms

(d) How E° values help select appropriate materials for dental implants and surgical instruments

Q16. Given the following standard reduction potentials:

E°(Fe³⁺/Fe²⁺) = +0.77 V

E°(Cu²⁺/Cu) = +0.34 V

E°(Zn²⁺/Zn) = -0.76 V

E°(Ag⁺/Ag) = +0.80 V

(a) Identify the strongest oxidising agent and the strongest reducing agent.

(b) Calculate the standard EMF of the cell: Zn | Zn²⁺ (1 M) || Cu²⁺ (1 M) | Cu

(c) Predict whether the reaction Fe³⁺ + Cu → Fe²⁺ + Cu²⁺ is spontaneous under standard conditions.

Q17. The standard electrode potentials of three metals A, B, and C are -1.2 V, +0.5 V, and -0.4 V respectively.

(a) Arrange the metals in order of increasing reducing power.

(b) Which metal will displace hydrogen from dilute HCl? Write the reaction.

(c) If B and C are connected to form a galvanic cell, identify the anode and cathode and calculate the cell EMF.

Q18. A calomel electrode (Hg | Hg₂Cl₂ | Cl⁻) has a standard potential of +0.27 V. It is used as a reference electrode to measure the electrode potential of an unknown metal M.

(a) If the measured cell EMF is 0.93 V with M as the anode, calculate E°(Mⁿ⁺/M).

(b) If the concentration of Mⁿ⁺ is changed to 0.01 M (temperature = 25°C, n = 2), calculate the new electrode potential using the Nernst equation.

(c) Identify metal M from standard electrode potential tables and suggest one practical application based on its E° value.