Electrolysis of Water

Also called

electrolysis · electrolytic decomposition · decomposition by electricity · hydrogen and oxygen 2:1 · cathode and anode · carbon electrodes · graphite rods · dilute sulphuric acid in water · pop test for hydrogen · glowing splint test for oxygen · water splitting · 2H2O → 2H2 + O2 · Hofmann voltameter · जल का विद्युत अपघटन · विद्युत अपघटन · हाइड्रोजन · ऑक्सीजन

Topics

• Passing an electric current through water splits it into hydrogen and oxygen: 2H₂O → 2H₂ + O₂.
• This is a decomposition reaction driven by electrical energy, so it is called electrolysis.
• Pure water hardly conducts; a few drops of dilute sulphuric acid let the current pass through it.
• Hydrogen gas collects over the cathode, the electrode joined to the negative terminal of the battery.
• Oxygen gas collects over the anode, the electrode joined to the positive terminal of the battery.
• The volume of hydrogen is twice the volume of oxygen, matching the 2 : 1 ratio in the equation.
• A burning splint at the mouth of the hydrogen tube goes off with a pop; a glowing splint relights in oxygen.
• Each water molecule holds two hydrogen atoms and one oxygen atom, which is why the gases come out 2 : 1.

About this model

A GLB file of about 399 KB, shown in Lably's 3D viewer and, on a phone, placed in your room with AR. Credit: Model, science and animation: Lably (built procedurally with three.js; no downloaded meshes). | CC BY 4.0. Original geometry and animation made for Lably.

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