A galvanic (voltaic) cell is an electrochemical cell that uses a thermodynamically favored redox reaction to generate electrical energy, producing a positive cell potential (E°cell > 0) and a negative ΔG° as electrons flow spontaneously from the anode to the cathode.
A galvanic cell (the CED also calls it a voltaic cell) is a setup that turns a spontaneous redox reaction into usable electricity. You split one redox reaction into two half-cells. Oxidation happens at the anode, reduction happens at the cathode, and electrons travel through an external wire from anode to cathode. That moving stream of electrons is the current the cell produces.
Per essential knowledge 9.8.A.1, every piece of the cell has a job. The electrodes are where the half-reactions actually occur, the solutions supply the ions being oxidized or reduced, the salt bridge lets ions migrate to keep each half-cell electrically neutral, and a voltmeter measures the potential difference. The defining feature is in 9.8.A.2 and 9.9.A.1. The reaction in a galvanic cell is thermodynamically favored, so the cell produces a positive voltage on its own. No battery or external power source needed. That single fact (E°cell > 0, therefore ΔG° < 0) is what separates a galvanic cell from everything else in electrochemistry.
Galvanic cells live in Unit 9 (Thermodynamics and Electrochemistry), specifically Topics 9.8 and 9.9. Learning objective 9.8.A asks you to connect the physical parts of the cell (electrodes, solutions, salt bridge) to how the cell actually operates, at both the macroscopic level (an electrode gains mass, a gas bubbles out) and the particulate level (this ion gets reduced at this surface). Learning objective 9.9.A asks you to judge whether a cell is thermodynamically favored using standard reduction potentials and E°cell. This is where the whole unit clicks together. The thermodynamics half of Unit 9 gave you ΔG° as the favorability test, and the galvanic cell is that idea made physical. A positive E°cell is just a negative ΔG° wearing electrochemistry clothes, linked by ΔG° = -nFE°.
Keep studying AP Chemistry Unit 9
Electrolytic Cell (Unit 9)
The mirror image of a galvanic cell. A galvanic cell runs a favored reaction and produces voltage; an electrolytic cell uses an external power source to force an unfavored reaction (negative E°cell) to happen. Same parts, opposite thermodynamics.
ΔG° = -nFE° and Gibbs Free Energy (Unit 9)
This equation is the bridge between the thermodynamics topics earlier in Unit 9 and electrochemistry. A galvanic cell has E°cell > 0, so ΔG° comes out negative, which is exactly what 'thermodynamically favored' meant back in Topic 9.5. One sign tells you the other.
Standard Reduction Potentials, E°red (Unit 9)
You build E°cell from a table of E°red values. The half-reaction with the more positive reduction potential runs as written at the cathode, and the other one flips to become the oxidation at the anode. That's how you predict which electrode is which in any galvanic cell.
Cell Potential Under Nonstandard Conditions (Unit 9)
Topic 9.9 extends galvanic cells beyond 1.0 M solutions. Change a concentration and you shift Q, which shifts the voltage, which is a Le Châtelier-style argument straight out of Unit 7. Increasing the concentration of a reactant ion pushes the cell potential up.
Galvanic cells show up on both multiple choice and FRQs, and the questions almost always test the E°cell ↔ ΔG° link or the anatomy of the cell. The 2018 short FRQ gave a Ag/Ag⁺ and Cr/Cr³⁺ galvanic cell and the 2025 short FRQ gave a Zn/Al cell where one electrode gains mass and the other loses mass. In both cases you have to identify which electrode is the anode and which is the cathode, write or combine half-reactions, calculate E°cell from standard reduction potentials, and explain favorability. Multiple-choice stems often hand you an E°cell value like +0.76 V or +0.28 V and ask what it implies about ΔG° and thermodynamic favorability, or ask which concentration change would increase the cell potential. Be ready to reason at the particulate level too, like explaining why the anode shrinks (its metal atoms are being oxidized into ions) or which way anions move through the salt bridge (toward the anode).
Both are electrochemical cells with electrodes, half-reactions, and the same anode/cathode definitions (oxidation at anode, reduction at cathode). The difference is the direction of energy flow. A galvanic cell runs a thermodynamically favored reaction (E°cell > 0, ΔG° < 0) and produces electricity. An electrolytic cell consumes electricity from an external source to drive a reaction that wouldn't happen on its own (E°cell < 0, ΔG° > 0). Quick check on the exam: if there's a battery in the diagram, it's electrolytic; if there's just a voltmeter, it's galvanic.
A galvanic (voltaic) cell converts a thermodynamically favored redox reaction into electrical energy, so its E°cell is always positive and its ΔG° is always negative.
Oxidation happens at the anode and reduction happens at the cathode, and electrons flow through the external wire from anode to cathode in every electrochemical cell.
The anode loses mass as its metal atoms are oxidized into ions, while the cathode gains mass as ions from solution are reduced and deposited.
You calculate E°cell by combining standard reduction potentials, where the half-reaction with the more positive E°red runs as the reduction at the cathode.
The salt bridge completes the circuit by letting ions flow between half-cells, keeping each solution electrically neutral so the reaction can keep running.
ΔG° = -nFE° ties electrochemistry back to thermodynamics, so any question about cell potential is secretly a question about Gibbs free energy.
A galvanic cell (also called a voltaic cell) is an electrochemical cell that uses a spontaneous, thermodynamically favored redox reaction to produce electricity. It always has a positive E°cell and a negative ΔG°, and it's tested in Unit 9 Topics 9.8 and 9.9.
Yes. Galvanic and voltaic are two names for the exact same thing, and the CED uses both. The AP exam may use either word, so treat them as interchangeable.
A galvanic cell produces electricity from a favored reaction (E°cell > 0), while an electrolytic cell needs an external power source to force an unfavored reaction (E°cell < 0). The diagram gives it away. A voltmeter means galvanic, a battery means electrolytic.
In a galvanic cell the anode is the negative electrode, because oxidation there releases electrons that flow out through the wire. Don't memorize signs as your main strategy, though. AP questions reward knowing that oxidation happens at the anode no matter what kind of cell it is.
The anode loses mass because its metal atoms are oxidized into ions that dissolve into solution. The 2025 FRQ tested exactly this, with a Zn electrode gaining mass (reduction at the cathode) while the Al electrode lost mass (oxidation at the anode).