Define anode and cathode.

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Q. Define anode and cathode.

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Concept understanding — Galvanic Cells and Cell Notation

A galvanic (voltaic) cell converts a spontaneous chemical reaction into a usable electric current, and it does so by physically separating the oxidation and reduction half-reactions into two half-cells joined by an external wire and a salt bridge. The Daniel cell is the archetype: a zinc strip in ZnSO4 solution (oxidation half-cell, $\text{Zn} \rightarrow \text{Zn}^{2+} + 2e^-$ ) is joined to a copper strip in CuSO4 solution (reduction half-cell, $\text{Cu}^{2+} + 2e^- \rightarrow \text{Cu}$ ) via an external wire and a salt bridge of agar-agar gel with an inert electrolyte such as KCl.

Electrons flow from the zinc anode (negative, as it steadily loses electrons) through the external wire to the copper cathode (positive, as it steadily consumes electrons), while the salt bridge maintains electrical neutrality in both compartments — Cl⁻ migrating into the anodic side to balance rising Zn²⁺, and K⁺ migrating into the cathodic side to balance falling Cu²⁺ — without ever letting the two solutions mix. The cell keeps running only until the zinc electrode is fully dissolved or the Cu²⁺ supply is fully reduced; where reactants or products cannot themselves serve as an electrode, an inert electrode such as graphite or platinum is used instead.

Galvanic cells are described compactly with IUPAC cell notation: the Daniel cell is written $\text{Zn(s)} \mid \text{Zn}^{2+}\text{(aq)}\ \|\ \text{Cu}^{2+}\text{(aq)} \mid \text{Cu(s)}$ . The anode is always written leftmost, the cathode rightmost; a single bar (|) marks a phase boundary; the double bar (||) marks the salt bridge; and the emf is written after the diagram. Reading the notation left to right retraces the electron's actual path through the external circuit — a shorthand that condenses the entire physical apparatus, and both half-reactions, into one line.

Step 1. In every electrochemical cell — galvanic or electrolytic — the anode is defined as the electrode at which OXIDATION takes place, i.e. the electrode where a species loses electrons.

Step 2. The cathode is defined as the electrode at which REDUCTION takes place, i.e. the electrode where a species gains electrons.

Step 3. This definition is universal, but the electrode's SIGN differs between the two cell types: in a galvanic cell, the anode is negative (it is spontaneously giving up electrons to the external circuit) and the cathode is positive; in an electrolytic cell, the anode is positive (connected to the positive terminal of the external supply, which pulls electrons away) and the cathode is negative (connected to the negative terminal, which pushes electrons in).

✓Final answer

Anode: the electrode where oxidation occurs. Cathode: the electrode where reduction occurs. (Their electrical sign depends on whether the cell is galvanic or electrolytic.)

Same / Similar Concept — real previous-year questions on the same or a closely similar concept, not this exact question.

CBSE 2026Set ANNUAL1 markMCQ
$Q. Which of the following statement is not correct about an inert electrode in a cell?$
(a) It does not participate in the cell reaction
(b) It provides surface either for oxidation or for reduction reaction.
(c) It provide surface for conduction of electrons
(d) It provide surface for redox reaction.
›Reveal solutionSolution
An inert electrode (like Pt or graphite) only supplies a conducting surface for ONE half-reaction (either oxidation or reduction) at a time; it never itself carries out the complete redox reaction.

An inert electrode does not participate chemically in the cell reaction — it is not consumed or oxidised/reduced itself. Its job is purely to:

Not participate in the cell reaction — true, since it stays chemically unchanged.

Provide a surface either for oxidation or for reduction — true; at the anode it hosts oxidation, at the cathode it hosts reduction, but never both at the same electrode.

Provide a surface for conduction of electrons — true, it allows electrons to flow into/out of the external circuit.

Provide a surface for the (complete) redox reaction — this is the incorrect statement. A single inert electrode only ever facilitates one half-reaction (oxidation OR reduction); the full redox reaction is the sum of both half-reactions occurring at the two separate electrodes, not at one electrode alone.

✓Final answer
$(d) "It provides surface for redox reaction" is NOT correct — a single inert electrode facilitates only one half-reaction (oxidation or reduction), never the complete redox process by itself.$
CBSE 2024Set ANNUAL1 markMCQ
$Q. Anode in an Electrochemical cell is that electrode on which the following is essential:$
(a) +ve charge
(b) -ve charge
(c) oxidation occurs
(d) reduction occurs
›Reveal solutionSolution

By definition, the anode is the electrode where oxidation (loss of electrons) takes place, in BOTH galvanic and electrolytic cells.

The anode/cathode identity is defined by the chemical process occurring there, not by charge sign (which flips between galvanic cells and electrolytic cells): oxidation always happens at the anode, and reduction always happens at the cathode. This is true whether the cell is a galvanic (voltaic) cell generating current spontaneously, or an electrolytic cell consuming external current — only the polarity (+/-) sign of the anode changes between the two cell types, never the reaction that occurs there.

✓Final answer
$Oxidation occurs at the anode (option c).$
CBSE 2021Set TERM11 mark
$Q. Define Galvanic cell.$
›Reveal solutionSolution

A galvanic (voltaic) cell is a device that generates an electric current from a spontaneous redox reaction occurring in two separate half-cells.

A Galvanic cell (also called a voltaic cell) is an electrochemical device that converts the chemical energy released in a spontaneous redox reaction directly into electrical energy. It consists of two half-cells (electrode dipped in electrolyte solution) connected by a salt bridge and an external wire; oxidation occurs at the anode and reduction at the cathode, driving electrons through the external circuit. Example: the Daniell cell, $Zn(s) | ZnSO_4(aq) \| CuSO_4(aq) | Cu(s)$ .

✓Final answer
$A Galvanic cell converts the chemical energy of a spontaneous redox reaction into electrical energy (e.g., the Daniell cell).$
CBSE 2017Set ANNUAL1 markMCQ
$Q. In a galvanic cell, which one of the following statements is not correct?$
(a) Anode is negatively charged
(b) Cathode is positively charged
(c) Reduction takes place at the anode
(d) Reduction takes place at the cathode
›Reveal solutionSolution
In any electrochemical cell, oxidation always occurs at the anode and reduction always occurs at the cathode — so statement (c) is false.

In a galvanic cell:

The anode is the electrode where oxidation occurs (electrons are released), and because electrons accumulate there and flow out towards the external circuit, the anode is the negative electrode. Statement (a) is correct.

The cathode is where reduction occurs, and it is the positive electrode. Statement (b) is correct.

Statement (c), "reduction takes place at the anode," contradicts the basic definition — reduction happens at the cathode, not the anode. This statement is INCORRECT.

Statement (d), "reduction takes place at the cathode," is correct by definition.

✓Final answer
$(c) is the statement that is NOT correct — reduction actually occurs at the cathode, not the anode.$

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Q.Define anode and cathode.

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