Galvanic Cells and Electrode Potential

topicmedium99 MCQ

Cell representation, EMF and the standard hydrogen electrode. (Chemistry › Electrochemistry, NEET UG syllabus.)

What is Galvanic Cells and Electrode Potential?

An electrochemical cell that converts chemical energy into electrical energy through a spontaneous redox reaction.

Key formula / rule: Standard Cell Potential

Confusing anode and cathode, or their signs (anode is negative in galvanic cells, positive in electrolytic cells).

Term: Galvanic Cell (Voltaic Cell)
Meaning: An electrochemical cell that converts chemical energy into electrical energy through a spontaneous redox reaction.

Term: Electrode Potential
Meaning: The potential difference developed between a metal electrode and its electrolyte solution when they are in contact.

Term: Standard Electrode Potential (E°)
Meaning: The electrode potential measured under standard conditions (1 M concentration for ions, 1 atm pressure for gases, 298 K temperature) relative to the Standard Hydrogen Electrode.

Term: Standard Hydrogen Electrode (SHE)
Meaning: A reference electrode assigned a standard electrode potential of 0.00 V, consisting of a platinum electrode in contact with 1 M H⁺ ions and H₂ gas at 1 atm pressure.

Term: Anode
Meaning: The electrode where oxidation occurs; it is the negative terminal in a galvanic cell.

Term: Cathode
Meaning: The electrode where reduction occurs; it is the positive terminal in a galvanic cell.

Term: Salt Bridge
Meaning: A U-shaped tube containing an inert electrolyte (e.g., KCl) that connects the two half-cells of a galvanic cell, maintaining electrical neutrality by allowing ion migration.

Term: Electromotive Force (EMF) / Cell Potential
Meaning: The potential difference between the two electrodes of a galvanic cell when no current is drawn from the cell.

Define galvanic cells and explain their working principle.
Identify anode, cathode, and the direction of electron flow in a galvanic cell.
Explain the function of a salt bridge.
Represent a galvanic cell using standard cell notation.
Define electrode potential and standard electrode potential.
Describe the Standard Hydrogen Electrode (SHE) and its significance.
Calculate the standard cell potential (E°cell) from standard electrode potentials.
Predict the spontaneity of a redox reaction based on E°cell.

Name: Standard Gibbs Free Energy Change
Note: n = number of moles of electrons transferred, F = Faraday constant (96485 C/mol). A negative ΔG° corresponds to a positive E°cell for spontaneity.
Expression: ΔG° = -nFE°cell

Basic understanding of redox reactions (oxidation, reduction, oxidizing agent, reducing agent).
Knowledge of balancing redox reactions.
Concept of half-reactions.
Basic stoichiometry.

Confusing anode and cathode, or their signs (anode is negative in galvanic cells, positive in electrolytic cells).
Incorrectly writing cell notation (anode | anode electrolyte || cathode electrolyte | cathode).
Not understanding the role of the salt bridge.
Using oxidation potentials instead of reduction potentials in E°cell calculations (always use standard reduction potentials for E°cell = E°cathode - E°anode).
Forgetting standard conditions (1 M, 1 atm, 298 K) for E°.
Assuming SHE is always the anode or cathode; its role depends on the other half-cell.

What is the standard electrode potential of the Standard Hydrogen Electrode (SHE) at 298 K?…
easy
What is the primary function of a salt bridge in a galvanic cell?…
easy
Which of the following is the correct cell representation for a galvanic cell with zinc and copper electrodes, given that Zn is oxidized and Cu2+ is reduced?…
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