Medium⏱ time40 min$ cost8
Electrolysis of Water
A battery splits water into hydrogen and oxygen bubbles you can collect and compare.
Start building ↓
Result first
The build
Step 01
Make electrodes
Connect each battery terminal to a graphite rod.
Step 02
Add electrolyte
Stir a little salt or baking soda into the water.
Step 03
Submerge
Dip both rods in; invert a tube over each.
Step 04
Collect gas
Watch bubbles rise — twice as much at one electrode.
Working Principle
Electric current splits water (2H₂O → 2H₂ + O₂): hydrogen forms at the negative electrode and oxygen at the positive.
The science behind it
A closer look
Because each water molecule has two hydrogens to one oxygen, you collect about twice the volume of hydrogen.
Take it further
Variables to test
- 1 Measure the gas ratio — is it really 2:1?
- 2 More salt — does it bubble faster? Why?
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