An electrode is a solid conductor where a half-reaction occurs and electric current enters or leaves an electrochemical or electrolytic cell; oxidation always happens at the anode and reduction always happens at the cathode, in both galvanic and electrolytic cells.
An electrode is the solid conductor (usually a metal strip or an inert material like platinum or graphite) sitting in each half-cell of an electrochemical cell. It's where the actual chemistry happens. Electrons flow into or out of the cell through the electrodes, and each one hosts a half-reaction. The anode is where oxidation occurs, and the cathode is where reduction occurs. That rule never changes, whether the cell is galvanic (spontaneous) or electrolytic (driven by an outside voltage).
Electrodes come in two flavors. An active electrode participates in the reaction, so it gains or loses mass as the cell runs. In the 2025 FRQ, a Zn electrode gained mass (Zn²⁺ was being reduced onto it) while the Al electrode lost mass (Al was being oxidized away). An inert electrode just conducts electrons without reacting, like the inert electrodes used to electrolyze molten MgCl₂ in the 2021 FRQ. Either way, the electrode is your window into the cell. Watching which electrode grows and which one shrinks tells you the direction of electron flow and which half-reaction is which.
Electrodes live in Unit 9 (Thermodynamics and Electrochemistry), especially Topic 9.10 on electrolysis and Faraday's Law. They also support learning objective 9.10.A, which asks you to explain how cell potential changes under nonstandard conditions. Per EK 9.10.A.1, the concentrations of the active species around each electrode determine how far the system is from equilibrium, and the cell potential is the driving force toward that equilibrium. So when a question changes the concentration in one half-cell, you're really being asked how conditions at an electrode shift Q and therefore E. On the quantitative side, Faraday's Law connects current through the electrodes to the mass of substance deposited or dissolved at them. That electrode-level stoichiometry is one of the most reliable calculation setups on the exam.
Electrochemical Cell (Unit 9)
An electrochemical cell is basically two electrodes, two solutions, and a connection between them. Every cell diagram on the exam starts with identifying which electrode is the anode and which is the cathode, then everything else (electron flow, mass changes, sign of E°) follows from that.
Faraday's Law (Unit 9)
Faraday's Law turns electrode chemistry into math. Charge passed (q = I × t) divided by the Faraday constant gives you moles of electrons, and the half-reaction at each electrode converts that into grams deposited or dissolved. The classic problem gives you the mass of silver plated at one electrode and asks for the mass of copper at the other.
Redox Reaction (Unit 9)
Electrodes physically separate the two halves of a redox reaction. Oxidation at the anode releases electrons, reduction at the cathode consumes them, and the wire between the electrodes is what makes the electron transfer usable as current. If you can split a redox equation into half-reactions, you can assign each one to an electrode.
Salt Bridge (Unit 9)
Electrodes carry electrons through the external wire, but that alone would build up charge in each half-cell and kill the reaction. The salt bridge completes the circuit by letting ions migrate, keeping the solution around each electrode electrically neutral so the cell keeps running.
Electrodes show up constantly in Unit 9 questions, in two main ways. First, identification and reasoning. The 2018 FRQ gave a galvanic cell with Ag and Cr electrodes and asked about cell behavior, and the 2025 FRQ told you the Zn electrode gained mass while the Al electrode lost mass, then expected you to figure out which was the cathode and which was the anode from that. If an electrode gains mass, cations are being reduced onto it, so it's the cathode. Second, calculation. The 2021 FRQ used inert electrodes to electrolyze molten MgCl₂ and asked Faraday's Law math, and multiple-choice questions often give a current and time (or a mass deposited at one electrode) and ask for the amount produced at another. The setup is always the same chain. Charge in coulombs, divide by 96,485 C/mol e⁻, then use the half-reaction stoichiometry at that electrode. You should also be ready for concentration cell setups, like a Zn electrode in 0.1 M solution paired with a Cu electrode in 2.5 M solution, where the question is testing whether you recognize nonstandard conditions (LO 9.10.A).
The electrode is the solid conductor where the half-reaction happens; the electrolyte is the ion-containing solution (or molten salt) it sits in. Electrons travel through the electrodes and the external wire, while ions travel through the electrolyte and salt bridge. A handy memory hook is that electrodes carry electrons and electrolytes carry ions. Mixing these up wrecks circuit-diagram questions, because electrons never swim through the solution.
An electrode is the solid conductor where a half-reaction occurs; oxidation always happens at the anode and reduction always happens at the cathode, in both galvanic and electrolytic cells.
If an electrode gains mass, cations from solution are being reduced onto it, so it's the cathode; if it loses mass, the metal is being oxidized into solution, so it's the anode.
Active electrodes participate in the reaction and change mass, while inert electrodes (like platinum or the ones used to electrolyze molten MgCl₂) only conduct electrons.
Faraday's Law connects electrodes to stoichiometry: charge equals current times time, moles of electrons equal charge divided by 96,485 C/mol, and the half-reaction at the electrode converts moles of electrons to grams of product.
Electrons flow through the electrodes and external wire, while ions flow through the electrolyte and salt bridge; both paths are needed for a complete circuit.
The concentrations of species around each electrode set how far the cell is from equilibrium, which determines the cell potential under nonstandard conditions (LO 9.10.A).
An electrode is the solid conductor in each half-cell where a half-reaction occurs and where current enters or leaves the cell. Oxidation happens at the anode and reduction happens at the cathode, and this is tested heavily in Unit 9 (Topic 9.10).
No. Oxidation happens at the anode and reduction at the cathode in every type of cell. What flips between galvanic and electrolytic cells is the sign convention (which electrode is + or −), not the chemistry. In the 2021 FRQ on molten MgCl₂, liquid Mg formed at the cathode (reduction) and Cl₂ gas at the anode (oxidation), exactly as the rule predicts.
The electrode is the solid conductor (metal strip, graphite rod) where the half-reaction happens; the electrolyte is the ion-containing solution or molten salt around it. Electrons move through electrodes and wires, while ions move through the electrolyte and salt bridge.
Look for the electrode gaining mass or producing a reduced product. On the 2025 FRQ, the Zn electrode increased in mass because Zn²⁺ ions were being reduced onto it, making it the cathode, while the Al electrode lost mass and was the anode.
Use Faraday's Law. Find the charge (q = I × t, in coulombs), divide by 96,485 C/mol to get moles of electrons, then use the electrode's half-reaction to convert to moles and grams of substance. A classic version gives you 3.21 g of Ag deposited at one electrode and asks how much Cu deposits at another in the same circuit.