A-Level Chemistry Revision — Electrode Potentials
Revise Electrode Potentials for A-Level Chemistry with a topic explanation, worked example and common mistakes. Check the board notes for specification differences.
At a glance
- What StudyVector is
- An exam-practice platform with board-aligned questions, explanations, and adaptive next steps.
- This topic
- Electrode Potentials in A-Level Chemistry: explanation, examples, and practice links on this page.
- Who it’s for
- Students revising A-Level Chemistry for UK exams.
- Exam boards
- Check your course page and the topic board notes for supported specifications.
- Free plan
- Sign up free to use tutor paths and feedback on your answers. Free access is Free daily revision · No card required. Pricing
- What makes it different
- Syllabus-shaped practice and progress tracking—not generic AI answers.
This page includes a topic explanation and a worked example. Check your course for current practice coverage.
Recommended next topic
Next step: Acids & Bases (A-Level)
Continue in the same course — structured practice and explanations on StudyVector.
Go to Acids & Bases (A-Level)Topic explanation
What is Electrode Potentials?
Electrode potentials quantify the tendency of a species to be reduced and gain electrons. Standard electrode potentials (E°) are measured relative to the standard hydrogen electrode (SHE) under standard conditions. These values are used to calculate the electromotive force (e.m.f.) of an electrochemical cell and to predict the feasibility of redox reactions. A more positive E° value indicates a greater tendency for a species to be reduced.
Board notes: All boards cover the calculation of cell e.m.f. and the prediction of redox reaction feasibility. AQA often includes questions on different types of electrochemical cells, including non-rechargeable, rechargeable, and fuel cells. Edexcel may focus on the industrial applications of electrolysis, linking it to electrode potentials. OCR frequently tests the construction of conventional cell diagrams and the role of the salt bridge.
Step-by-step explanationWorked examples
Worked example
Calculate the standard e.m.f. of a cell made from Cu2+/Cu (E° = +0.34V) and Zn2+/Zn (E° = -0.76V) half-cells. Step 1: Identify the positive and negative terminals. The Cu2+/Cu half-cell has the more positive E° value, so it is the positive terminal (where reduction occurs). The Zn2+/Zn half-cell is the negative terminal (where oxidation occurs). Step 2: Apply the formula E°cell = E°(positive) - E°(negative). Step 3: E°cell = (+0.34) - (-0.76) = +1.10V. Since the e.m.f. is positive, the reaction is feasible.
Practise this topic
Start with low-focus cards for Electrode Potentials, then move into full exam-style practice when you want the heavier session.
Common mistakes
- 1Getting the formula for cell e.m.f. the wrong way around. The correct formula is E°cell = E°(positive terminal) - E°(negative terminal), which is equivalent to E°(reduced species) - E°(oxidised species). The result must be positive for a feasible reaction.
- 2Confusing the direction of electron flow. In an electrochemical cell, electrons always flow from the more negative half-cell to the more positive half-cell, i.e., from the site of oxidation to the site of reduction.
- 3Forgetting that standard conditions are required for E° values to be valid. These conditions are 298K temperature, 1.00 mol dm-3 concentration of ions, and 100 kPa pressure for any gases.
Electrode Potentials exam questions
Check the available question sets for Electrode Potentials. Use your course and exam board to confirm which practice is relevant.
Electrode Potentials exam questionsGet help with Electrode Potentials
Get a personalised explanation for Electrode Potentials from the StudyVector tutor. Ask follow-up questions and work through problems with step-by-step support.
Open tutorSave your progress in Electrode Potentials
Start a free account for low-focus question cards, feedback and Play routes across available topics. Free daily limits apply; no card required.
Continue your revision
A public question for Electrode Potentials is still being reviewed. Your course page shows the topics currently available for practice.
Continue with Electrode Potentials
Create a free account to keep your course choice and save your practice progress.
Start free low-focus cardsAlready have an account? Log in
Frequently asked questions
What is the standard hydrogen electrode (SHE)?
The SHE is the reference standard for all other electrode potentials. It consists of hydrogen gas bubbling over a platinum electrode in a solution of H+ ions at 1 mol dm-3 concentration. Its electrode potential is defined as exactly 0.00V under standard conditions.
Can a reaction with a positive E°cell still not happen?
Yes. Standard electrode potentials only predict thermodynamic feasibility. They do not give any information about the rate of reaction. A reaction may have a very high activation energy, making it kinetically stable and proceed immeasurably slowly, even if it is thermodynamically feasible.