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Chemistry

Difference Between Galvanic Cells And Electrolytic Cells

Difference Between Galvanic Cells and Electrolytic Cells

Comparison Table: Galvanic vs Electrolytic Cells (Anode, Cathode, Examples & More)

The Difference Between Galvanic Cells and Electrolytic Cells is central to understanding electrochemistry in JEE Main. Both are types of electrochemical cells but operate on opposite principles—galvanic cells convert chemical energy into electrical energy via spontaneous redox reactions, while electrolytic cells use electrical energy to force non-spontaneous chemical changes. Clarity on these differences aids in tackling theory, MCQs, and application-based problems. This page gives a direct, exam-oriented comparison, including table, working principles, charge conventions, real-world uses, and tips for JEE accuracy.

Introduction to Galvanic Cells and Electrolytic Cells

Electrochemical cells are devices that involve the transfer of electrons through redox reactions, producing or consuming electrical current as a result. The two fundamental types are the galvanic cell (also called voltaic cell) and the electrolytic cell. Both employ electrodes and electrolytes but differ in their energy conversion direction and spontaneity of reaction. The difference between galvanic cell and electrolytic cell has significant implications for JEE Main, both in direct questions and numericals.

In a galvanic cell, energy is released from a spontaneous chemical reaction and converted into electricity. In contrast, an electrolytic cell requires an externally applied electric current to drive a non-spontaneous reaction. Both types involve oxidation at the anode and reduction at the cathode, but their charge assignments flip, which can trip students in competitive exams.

Difference Between Galvanic Cell and Electrolytic Cell (Table)

Galvanic cell vs electrolytic cell comparison is vital for clarity in JEE. The following table provides a structured point-by-point contrast to focus on high-yield exam concepts:

Property	Galvanic Cell	Electrolytic Cell
Energy Conversion	Chemical → Electrical	Electrical → Chemical
Type of Reaction	Spontaneous redox (ΔG < 0)	Non-spontaneous redox (ΔG > 0)
Source of Energy	Generated by cell reactions	Supplied by external battery
Anode Polarity	Negative	Positive
Cathode Polarity	Positive	Negative
Electron Flow	From anode to cathode (via external circuit)	From anode to cathode (forced by power source)
Half-Cell Arrangement	Separate containers linked by salt bridge	Both electrodes in one electrolyte solution
Salt Bridge Use	Essential for ion migration	Not essential (often omitted)
Example	Daniel cell, dry cell, batteries	Electrolysis of NaCl(l), electroplating
Main Application	Electricity generation	Chemical synthesis, metal extraction

Remember: Both types involve redox reactions, but the driving force and electrode polarity are opposite. Focus on language like “spontaneous” and “non-spontaneous” to determine cell type in MCQs.

Working Principle and Diagrams

The operation of each cell follows distinct principles. For JEE Main, understanding how electron and ion flows create cell potential and the impact on electrode charges is essential for problem-solving and diagram-based questions.

Galvanic Cell Working: Oxidation at negative anode releases electrons, which flow through an external wire to the positive cathode where reduction occurs. Ions migrate via a salt bridge to maintain charge balance. Example: In the Daniel Cell, Zn(s) | Zn²⁺ (anode) and Cu²⁺ | Cu(s) (cathode).
Electrolytic Cell Working: External battery pushes electrons into the negative cathode, forcing non-spontaneous reduction. Positive anode attracts anions, causing oxidation. Both electrodes are dipped in one electrolyte solution. Example: Electrolysis of molten NaCl—Na⁺ is reduced at cathode; Cl^– is oxidized at anode.

Diagrams often label anode and cathode, arrows for electron flow, electrolyte, and (for a galvanic cell) the salt bridge. For written tests, clearly show charge signs and reaction sites on your cell diagram. Practice with JEE Main previous year questions for confidence.

Anode vs Cathode: Polarity, Reactions and Mnemonics

To avoid confusion, focus on three core points in comparing anode and cathode in both cells:

Oxidation always occurs at the anode, reduction at the cathode (OIL RIG: Oxidation Is Loss, Reduction Is Gain of electrons).
In a galvanic cell: Anode is negative, cathode is positive (electrons released from anode).
In an electrolytic cell: Anode is positive, cathode is negative (electrons forced by external supply).
Electron flow is always from anode to cathode, but direction relative to battery changes between cell types.

Mnemonic to remember:

AN OX: Anode = Oxidation (in both cells)
RED CAT: Reduction = Cathode (in both cells)
“Galvanic Gives” (G for Galvanic, G for Gives electrons at anode)
“Electrolytic Eats” (E for Electrolytic, E for Eats electrons at cathode)

This logic helps in fast MCQ solving and avoids mistakes on electrode polarity assignments in numericals.

Examples and Real-World Applications

Galvanic cells are used in everyday batteries—AA cells, car batteries, and even in biological cells (nerve impulses involve similar principles). The Daniel Cell (Zn–Cu cell) is a standard JEE example for calculation questions.

Electrolytic cells are used in industrial electrolysis (e.g., extracting aluminium, electroplating jewellery, and producing chlorine gas). An electrolytic cell’s main function is chemical synthesis, not power generation. Electrolysis of brine solution to make NaOH and Cl₂ gas is a classic example covered in JEE syllabus.

Everyday examples: Rechargeable batteries (can operate in both modes on charging/discharging), electrolysis for water splitting.
Industrial examples: Electroplating and extraction of metals.

For more, see Redox Reactions and Electrochemistry and Primary vs Secondary Cell.

Conversion: Galvanic Cell to Electrolytic Cell

A galvanic cell can become an electrolytic cell if an external voltage greater than its EMF is applied in reverse. The spontaneous direction of the redox reaction reverses as the applied voltage overcomes the cell’s potential, and the cell drives the reverse (non-spontaneous) reaction. This concept is often examined in JEE when discussing charging and discharging of secondary (rechargeable) batteries or in electrolysis reversal situations.

For example, in a lead-acid battery, discharging is galvanic action; charging applies an external emf, making it electrolytic. This reversible action is key in battery chemistry and relevant for advanced problem-solving.

Summary: Key Differences and JEE Checklist

Galvanic Cell: Chemical to electrical energy, spontaneous, anode (-), cathode (+), used in batteries.
Electrolytic Cell: Electrical to chemical energy, non-spontaneous, anode (+), cathode (-), used in electrolysis.
Oxidation at anode, reduction at cathode for both.
Galvanic cells have separate containers (salt bridge); electrolytic cells usually have both electrodes in one solution.
JEE trap: Polarity of anode/cathode flips between the two cell types.
Real-life: Galvanic (dry cells, car batteries); Electrolytic (electroplating, metal extraction).
Reversible if >EMF applied against galvanic cell; taught via rechargeable cell examples.

Candidates should practice diagrams, sign conventions and example-based problems to master the difference between galvanic cell and electrolytic cell for JEE Main. Refer to Vedantu’s JEE Chemistry modules and redox reaction notes for more exam-ready resources.

FAQs on Difference Between Galvanic Cells and Electrolytic Cells

1. What is the difference between galvanic cell and electrolytic cell?

The main difference between a galvanic cell and an electrolytic cell is the source and direction of energy conversion.

Galvanic cells (voltaic cells) generate electrical energy from a spontaneous redox reaction.
Electrolytic cells use electrical energy to drive a non-spontaneous chemical reaction.
In galvanic cells, the anode is negative and the cathode is positive.
In electrolytic cells, the anode is positive and the cathode is negative.

2. Why is the anode negative in galvanic cells but positive in electrolytic cells?

The difference in anode polarity is based on the direction of electron flow and the type of reaction.

In a galvanic cell, electrons are produced at the anode (where oxidation occurs), making it negative.
In an electrolytic cell, the anode is connected to the positive terminal of the battery and attracts anions, so it's positive (even though oxidation occurs here too).
Remember: anode is always the site of oxidation, but polarity depends on cell type.

3. Can a galvanic cell become an electrolytic cell?

Yes, a galvanic cell can function as an electrolytic cell if an external voltage greater than its EMF is applied in the reverse direction.

The applied voltage forces the non-spontaneous reaction to occur (reverse process).
This is seen in rechargeable batteries during the charging process.
Example: During recharging of a lead-acid battery, it acts as an electrolytic cell.

4. What are some real-life examples of galvanic and electrolytic cells?

Examples of galvanic and electrolytic cells can be found in everyday devices and industrial processes.

Galvanic Cell Example: Dry cell batteries (like AA, AAA cells), Daniell cell, and car batteries during use.
Electrolytic Cell Example: Electroplating (silver or gold plating), electrolysis of water, and charging of rechargeable batteries.

5. What is the main function of the electrolyte in both cells?

The electrolyte allows the movement of ions to maintain electrical neutrality and complete the circuit.

In galvanic cells, it enables ion migration between electrodes (e.g., salt bridge).
In electrolytic cells, it conducts electricity and provides ions for the redox reactions.

6. Is a voltaic cell the same as a galvanic cell?

Yes, a voltaic cell and a galvanic cell refer to the same type of electrochemical cell that generates electricity from a spontaneous chemical reaction.

Both terms are used interchangeably in textbooks and exams.
They convert chemical energy into electrical energy through redox reactions.

7. Does electron flow direction change between the two cell types?

The direction of electron flow is always from anode to cathode, but their relative polarities differ.

In galvanic cells: electrons flow from negative anode to positive cathode spontaneously.
In electrolytic cells: electrons are pushed from external source, from positive anode to negative cathode (non-spontaneous direction).

8. Can you use the same materials for both cells in an experiment?

The same electrode materials and electrolytes can sometimes be used, but the selection depends on the desired reaction and cell type.

For certain redox couples, switching the direction of current can change a galvanic cell to an electrolytic cell using the same substances.
Electroylsis (electrolytic cell) often uses inert electrodes like platinum or graphite, while galvanic cells may use reactive metals.

9. What common mistakes do students make about anode/cathode polarity?

Students often confuse the charges of anode and cathode in galvanic and electrolytic cells.

Thinking anode is always negative – it's true only for galvanic/voltaic cells.
Forgetting that oxidation always occurs at the anode and reduction at the cathode, regardless of cell type.
Mixing up electron flow: always from anode to cathode (outside cell), but the source of electrons changes with cell type.

10. How do these differences affect MCQs in JEE Main?

Understanding the correct differences helps answer theory, MCQ, and reasoning questions accurately in JEE Main and NEET.

MCQs often test polarity, cell reactions, direction of electron/ion flow, and examples of each type.
Careful reading of whether the cell is galvanic or electrolytic is essential to avoid errors.
Memorizing the comparison table and the role of each component helps in quick recall during exams.