Electrochemical cell and electrode potentials are core topics for B. Pharm students studying redox chemistry, thermodynamics, and analytical techniques. This introduction covers galvanic and electrolytic cells, standard electrode potential (E°), electrode notation, the Nernst equation, and the ΔG = −nFE relationship. You will learn how concentration, temperature, and electron transfer number affect cell emf, and why reference electrodes (SHE, SCE), potentiometry, ion-selective electrodes, and voltammetric methods matter in drug analysis, stability testing, and sensor design. Emphasis is on concept-based calculations and pharmaceutical applications to strengthen exam and lab readiness. Now let’s test your knowledge with 30 MCQs on this topic.
Q1. In a galvanic (voltaic) cell, oxidation occurs at the
- Anode
- Cathode
- Salt bridge
- Electrolyte solution
Correct Answer: Anode
Q2. Electrons in an electrochemical cell flow from the
- Cathode to anode
- Anode to cathode
- Salt bridge to anode
- Solution to electrode
Correct Answer: Anode to cathode
Q3. The standard hydrogen electrode (SHE) is assigned what standard potential?
- +0.34 V
- −0.76 V
- 0 V
- +0.244 V
Correct Answer: 0 V
Q4. Which equation correctly relates Gibbs free energy change and cell potential?
- ΔG = nFE
- ΔG = +nFE
- ΔG = −nFE
- ΔG = −RT ln K
Correct Answer: ΔG = −nFE
Q5. At 25°C the factor 0.0592 in the Nernst equation (E = E° − 0.0592/n log Q) equals
- RT/F
- RT/F × ln10
- F/RT
- nRT/F
Correct Answer: RT/F × ln10
Q6. Given half-reactions Cu2+ + 2e− → Cu (E° = +0.34 V) and Zn2+ + 2e− → Zn (E° = −0.76 V), which half-cell is the cathode in the spontaneous cell?
- Zn/Zn2+
- Cu/Cu2+
- Salt bridge
- They are both anodes
Correct Answer: Cu/Cu2+
Q7. A positive standard cell potential (E°cell > 0) indicates that the reaction is
- non-spontaneous
- at equilibrium
- spontaneous as written
- dependent on the salt bridge
Correct Answer: spontaneous as written
Q8. In cell notation Zn | Zn2+ || Cu2+ | Cu, which species acts as the reducing agent?
- Zn2+
- Cu2+
- Zn
- Cu
Correct Answer: Zn
Q9. The primary function of a salt bridge in an electrochemical cell is to
- generate electrons
- maintain electrical neutrality by ion migration
- increase cell voltage
- act as the cathode
Correct Answer: maintain electrical neutrality by ion migration
Q10. For a half-reaction Ox + ne− → Red, increasing the concentration of Ox (oxidized form) will generally
- decrease the reduction potential
- have no effect on potential
- increase the reduction potential
- reverse the sign of E°
Correct Answer: increase the reduction potential
Q11. How many electrons are transferred in the redox reaction: 2Ag+ + Cu → 2Ag + Cu2+ ?
- 1
- 2
- 4
- 0
Correct Answer: 2
Q12. Which electrode type is commonly used for potentiometric pH measurement?
- Platinum electrode
- Glass electrode
- Mercury electrode
- Saturated calomel electrode
Correct Answer: Glass electrode
Q13. The saturated calomel electrode (SCE) is best described as a
- reference electrode containing Hg/Hg2Cl2
- working electrode for voltammetry
- type of ion-selective electrode for H+
- concentration cell
Correct Answer: reference electrode containing Hg/Hg2Cl2
Q14. Cell potential is an example of which kind of property?
- Extensive (depends on amount)
- Intensive (independent of amount)
- Depends on total charge only
- Proportional to salt bridge volume
Correct Answer: Intensive (independent of amount)
Q15. A concentration cell generates an emf because of
- different electrode materials
- different concentrations of the same redox couple
- dissimilar temperatures
- an external power source
Correct Answer: different concentrations of the same redox couple
Q16. Faraday’s constant (F) represents
- The voltage per electron
- The charge of one mole of electrons
- The number of electrons in one atom
- The mass of one mole of electrons
Correct Answer: The charge of one mole of electrons
Q17. An electrolytic cell requires an external power source because
- it produces spontaneous electrical energy
- it drives a non-spontaneous redox reaction
- the salt bridge is absent
- it contains gaseous electrodes
Correct Answer: it drives a non-spontaneous redox reaction
Q18. If E°cell is positive, the equilibrium constant K for the cell reaction will be
- less than 1
- equal to 1
- greater than 1
- equal to 0
Correct Answer: greater than 1
Q19. Which electrochemical technique measures current as a function of applied potential and is widely used in pharmaceutical analysis?
- Potentiometry
- Voltammetry
- Titrimetry
- Gravimetry
Correct Answer: Voltammetry
Q20. Which electrode material is commonly used as an inert conductor for electron transfer in electrochemical cells?
- Zinc
- Lead
- Platinum
- Silver chloride
Correct Answer: Platinum
Q21. In the half-reaction Fe3+ + e− → Fe2+, the species that acts as the oxidizing agent is
- Fe2+
- Fe3+
- e−
- H+
Correct Answer: Fe3+
Q22. The potential of the hydrogen electrode changes by approximately 0.0592 V per pH unit at 25°C. An increase of one pH unit makes the potential
- more positive by 0.0592 V
- more negative by 0.0592 V
- unchanged
- oscillate
Correct Answer: more negative by 0.0592 V
Q23. Which factors affect the electrode potential of a half-cell?
- Only concentration
- Concentration and temperature only
- Concentration, temperature, and pressure (for gaseous species)
- Only electrode surface area
Correct Answer: Concentration, temperature, and pressure (for gaseous species)
Q24. A salt bridge typically contains a concentrated solution of an inert electrolyte (e.g., KCl). Its main purpose is to
- increase cell emf by chemical reaction
- provide mobile ions that maintain charge balance without reacting chemically with electrodes
- act as the working electrode
- absorb hydrogen gas
Correct Answer: provide mobile ions that maintain charge balance without reacting chemically with electrodes
Q25. Which setup best describes a concentration cell used in potentiometric measurements?
- Dissimilar metal electrodes in identical concentrations
- Same electrode materials with different ion concentrations in two compartments
- Two identical half-cells connected with an external battery
- Reference electrode and ISE in a single solution
Correct Answer: Same electrode materials with different ion concentrations in two compartments
Q26. Ion-selective electrodes (ISEs) respond primarily to the
- total molar concentration of the ion
- activity (effective concentration) of the ion
- mass of the ion
- electrode surface area
Correct Answer: activity (effective concentration) of the ion
Q27. In potentiometric measurements the potential is measured under what condition to obtain a true electrode potential?
- High current through the cell
- Zero or negligible current (open-circuit)
- Short-circuited electrodes
- Rapid stirring causing high ionic flux
Correct Answer: Zero or negligible current (open-circuit)
Q28. The standard cell potential for the Daniell cell (Zn | Zn2+ || Cu2+ | Cu) using E°(Cu2+/Cu)=+0.34 V and E°(Zn2+/Zn)=−0.76 V is approximately
- −1.10 V
- 0 V
- +1.10 V
- +0.42 V
Correct Answer: +1.10 V
Q29. Standard conditions when quoting E° values usually mean
- 1 M concentrations, 1 atm pressure (for gases), and 25°C
- 0.1 M concentrations and 50°C
- Pure solids only at any temperature
- No solvents present
Correct Answer: 1 M concentrations, 1 atm pressure (for gases), and 25°C
Q30. For trace metal determination in pharmaceutical samples, which electrochemical method is especially sensitive?
- Bulk titration
- Anodic stripping voltammetry
- Gravimetric analysis
- Direct spectrophotometry without electrodes
Correct Answer: Anodic stripping voltammetry
I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.
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