Electrochemical Cells
Construct simple and half-cell systems, explain the salt bridge, predict voltage and electron direction, and write cell redox equations.
How to study National 5 Chemistry
Move between particle explanations, formulae, calculations, experimental evidence and justified conclusions, while using official materials for exact written-paper and assignment practice.
Core concepts
Concept 1
A simple cell uses two different electrodes in an electrolyte; two half-cells can be linked by an ion bridge to complete the circuit.
Exam cue: Show both the external electron path and the ionic connection when explaining a complete circuit.
Concept 2
Different element pairs produce different voltages, and elements farther apart in the electrochemical series generally produce a greater voltage.
Exam cue: Use the electrochemical series positions to predict electron direction.
Concept 3
Electrons flow externally from the species higher in the electrochemical series to the one lower, while paired ion-electron equations describe oxidation and reduction.
Exam cue: Include a graphite electrode when a half-cell has no conducting metal species.
Risk pitfalls and guardrails
Describing electrons as moving through the salt bridge.
Guardrail: Check formulae, charges, units, state or experimental conditions before committing to the final conclusion.
Assuming the physically larger electrode produces the greater voltage.
Guardrail: Check formulae, charges, units, state or experimental conditions before committing to the final conclusion.
Writing two oxidation or two reduction half-equations for one working cell.
Guardrail: Check formulae, charges, units, state or experimental conditions before committing to the final conclusion.
Memory anchors
Electrolyte
An electrolyte is a conducting liquid or solution containing mobile ions.
Half-cell
A half-cell pairs a redox species with an electrode.
Salt bridge
A salt bridge lets ions move and completes the electrical circuit between half-cells.
Cell voltage
Elements farther apart in the electrochemical series generally give a larger voltage.
Electron direction
Electrons flow externally from higher to lower in the electrochemical series.
Graphite electrode
Graphite can provide a conducting surface when no metal electrode participates.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What is an electrolyte?
What is needed to make a simple electrochemical cell?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
What is Pass Harbor?
Completely free exam prep for 247 UK exams.
- Practice questions
- Flashcards
- Study guides
- Mock exams
- No registration
- No paywall
- Start instantly
“No more expensive exam prep. Quality study tools should be accessible to everyone.”