Electrolysis of Aqueous Solutions with Inert Electrodes
ChemistryElectrochemistryAges 17–18Virtual lab
Use it with your class: students open it from a link or a QR code, with no account needed.
Next in Electrochemistry
Electrolyse an aqueous solution of CuSO₄, NaCl or Na₂SO₄ using graphite electrodes. The simulation shows which species is actually discharged at each electrode (Cu deposits on the cathode, H₂/O₂/Cl₂ gas is released) and calculates the mass or volume of product using Faraday's law m = A·I·t/(n·F).
Lesson: Electrolysis
What it shows
In the electrolysis of an aqueous solution, cations migrate to the cathode and anions to the anode, but the species discharged is not always an ion from the salt, because water competes at both electrodes. Cu²⁺ is reduced more easily than water, whereas Na⁺ is not, so NaCl gives hydrogen at the cathode and chlorine at the anode, and Na₂SO₄ solution simply splits water into H₂ and O₂ in a 2 : 1 volume ratio. The charge passed, q = I·t, fixes the amount of product through Faraday's law.
How to use
Pick an Electrolyte solution and set the Current, then let the cell run while the charge, moles of electrons and product mass or gas volume update. Tick Slow, to watch ions to follow the cations and anions migrating. Use Restart to repeat at a different current and compare the amounts formed after the same time; Pause lets students check the Faraday calculation by hand.
Parameters you can change
- Electrolyte solution CuSO₄ (inert electrodes), NaCl (inert electrodes), Na₂SO₄ (inert electrodes)
- Current 0.1–5 A
- Simulation speed 1–60 ×
Questions to explore
- Why is no sodium metal produced when NaCl or Na₂SO₄ solution is electrolysed?
- How does the mass of copper deposited change when you double the current for the same time?
- Why is the volume of H₂ twice the volume of O₂ when Na₂SO₄ solution is electrolysed?
