--- title: "Standard Electrode Potentials and Predicting Redox Reactions" description: "Each half reaction gets a potential measured against a standard hydrogen electrode. Put two half cells together and the difference says which way the electrons will flow, and whether a proposed reacti" canonical: https://lightmysky.com/learn/science/standard-electrode-potentials-and-predicting-redox-reactions-mt_LDI10CjoAI source: https://lightmysky.com/learn/science/standard-electrode-potentials-and-predicting-redox-reactions-mt_LDI10CjoAI.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Standard Electrode Potentials and Predicting Redox Reactions Each half reaction gets a potential measured against a standard hydrogen electrode. Put two half cells together and the difference says which way the electrons will flow, and whether a proposed reaction goes at all. Subject: Science · Area: Chemistry · Ages 17 to 18 Page: https://lightmysky.com/learn/science/standard-electrode-potentials-and-predicting-redox-reactions-mt_LDI10CjoAI ## Ready when they can - Describes a half cell and explains what the standard hydrogen electrode is there for - States the conditions a standard electrode potential is measured under and why they are fixed - Calculates a cell potential from two standard values and identifies which species is oxidised - Predicts whether a named redox reaction happens, and gives one reason a feasible one may still not be seen ## Lesson: Electrode potentials predict the winner A half cell pairs an element with its ions, such as zinc sitting in zinc ion solution. The standard hydrogen electrode, hydrogen gas over platinum in 1 M H+, is given 0.00 V so every other value has a baseline to stand on. Standard means fixed conditions: 298 K, 100 kPa, and 1.00 mol per cubic decimetre ions. Keeping them fixed lets every value compare fairly with every other one. **Example.** Zinc is -0.76 V and copper is +0.34 V, so the cell potential is 0.34 minus -0.76, which is +1.10 V. Zinc is the negative end: it gives up electrons and its atoms enter the solution as ions, while copper ions plate out. **Tip.** A positive cell potential means the reaction as written can go, while a negative one means it will not. Even a feasible one can stall on kinetics: hydrogen and oxygen sit mixed until a spark sets them off. **Recap.** Half cells stand on the hydrogen zero, standard conditions keep values fair, differences give voltages, and kinetics can still say wait. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Oxidation Numbers and Balancing Redox Equations](https://lightmysky.com/learn/science/oxidation-numbers-and-balancing-redox-equations-mt_4xuYKYgUex) - [Electrolysis: Half Equations at the Electrodes](https://lightmysky.com/learn/science/electrolysis-half-equations-at-the-electrodes-mt_6FvxaD8wTY) - [Free Energy and Whether a Reaction Is Feasible](https://lightmysky.com/learn/science/free-energy-and-whether-a-reaction-is-feasible-mt_o1kZgBYWoM) ## Opens up - [Metabolic Diversity: Choosing an Electron Donor and Acceptor](https://lightmysky.com/learn/science/metabolic-diversity-choosing-an-electron-donor-and-acceptor-mt__2yCr9OSIn) - [Redox Potentials and the Proton-Motive Force](https://lightmysky.com/learn/science/redox-potentials-and-the-proton-motive-force-mt_lU8kgepFRN) - [Cells That Do Work: Batteries, Fuel Cells and Corrosion](https://lightmysky.com/learn/science/cells-that-do-work-batteries-fuel-cells-and-corrosion-mt_NQQzlecX4v) - [Redox Titrations with Manganate(VII) and Thiosulfate](https://lightmysky.com/learn/science/redox-titrations-with-manganate-vii-and-thiosulfate-mt_tKZTSfo0Ra) - [The Nernst Equation and Cells Away from Standard Conditions](https://lightmysky.com/learn/science/the-nernst-equation-and-cells-away-from-standard-conditions-mt_yqmRqDaadR)