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Two metals and two solutions make a battery. Where do the electrons come from?
Redox Reactions lab · Last updated: 16 October 2026
In this 3D lab, you build a simple battery from two metals dipped in two solutions and trace where the electrons come from. Redox reactions are behind batteries, rusting and even breathing, so seeing one metal give electrons to another makes a tricky chemistry idea clear and concrete.
What you'll discover
- Electrons leave the more reactive metal and travel through the wire to the less reactive one.
- Oxidation and reduction always happen together, so a battery needs both halves to work.
- Metals that sit further apart in the reactivity series push electrons harder and give a bigger voltage.
The science in plain words
Every battery runs on a redox reaction. Oxidation means losing electrons and reduction means gaining them, and the two always happen together: one substance can only lose electrons if another takes them. A handy memory aid is OIL RIG, short for oxidation is loss, reduction is gain.
In a classic cell, a strip of zinc sits in zinc sulfate solution and a strip of copper sits in copper sulfate solution. Zinc is more reactive than copper, so zinc atoms give up two electrons each and dissolve as zinc ions. The electrons cannot jump across the solutions, so they flow through the outside wire to the copper strip. There, copper ions from the solution pick them up and are deposited as copper metal. A salt bridge or porous barrier lets ions drift between the two solutions so the charges stay balanced and the current keeps flowing.
The further apart two metals sit in the reactivity series, the bigger the voltage: a zinc and copper cell gives about 1.1 volts. The same electron transfer explains rusting, where iron loses electrons to oxygen, and displacement reactions, where a more reactive metal pushes a less reactive one out of its salt solution.
Where it fits
- India, NCERT: Class 10 science, Chapter 1: Chemical Reactions and Equations
- India, NCERT: Class 10 science, Chapter 3: Metals and Non-metals
- India, NCERT: Electrochemical cells go beyond the NCERT syllabus for classes 6 to 10; the lab builds on Class 10 oxidation, reduction and the reactivity series.
- United States: Grades 9 to 12
- Next Generation Science Standards: HS-PS1-2
Common questions
What is a redox reaction?
A redox reaction is one in which electrons move from one substance to another. The substance that loses electrons is oxidised and the one that gains them is reduced. Burning, rusting, respiration and every battery you use all depend on redox reactions.
How does a battery make electricity?
Inside a battery, one material gives up electrons and another accepts them. The two are kept apart, so the electrons have to travel through an outside wire to get from one to the other. That flow of electrons through the wire is the current that lights a torch or runs a toy.
Why does zinc give its electrons to copper?
Zinc is more reactive than copper, which means its atoms lose their outer electrons more easily. When the two metals are joined in a cell, zinc atoms are oxidised to zinc ions while copper ions are reduced to copper metal, so electrons flow from the zinc side to the copper side.
Related labs
- Electrolysis: Split water into hydrogen and oxygen with a battery. Which gas do you get more of?
- Chemical Reactions: Molecules must crash hard enough to react. What makes that happen more often?
- Simple Circuits: Close the switch. What makes the bulbs brighter: more volts, fewer bulbs, or a different wiring?
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Try it yourself
The Redox Reactions lab is one of the interactive 3D science labs inside Taz. Change one thing, predict what will happen, then run it and watch. Labs open after you sign in.