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Electroplating and Faraday's Laws – Copper, Silver and Nickel Plating a Key or Spoon

ChemistryElectrochemistryAges 17–18

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An electroplating cell: the anode is a plate of the plating metal and the cathode is the object to be plated (a steel key or spoon). Choose the plating metal (Cu²⁺, Ag⁺, Ni²⁺), set the current I and the plating time; electrons flow along the wires, metal ions drift to the cathode and build up a coating. The charge Q = I·t, the mass deposited m = I·t·M/(n·F) and the coating thickness update live, and a graph of m against t compares the three metals.

Lesson: Electrolysis with an active anode: electroplating; Faraday's laws and the mass of product at an electrode

What it shows

In electroplating the object is the cathode and a plate of the coating metal is the anode. Metal ions gain electrons at the cathode and deposit as metal, while the anode dissolves and keeps the ion concentration almost constant. Faraday's laws link the mass deposited to the charge passed: Q = I·t and m = Q·M/(n·F), with F = 96485 C/mol. Silver ions need one electron each and silver has a large molar mass, so silver deposits most per coulomb. The model assumes 100 % current efficiency and an even coating, and speeds up time.

How to use

Choose Copper plating, keep the steel key, set I and Plating time, then press Start plating and watch electrons, ions and the growing coat. Record m for several currents and times to show m ∝ I·t. Switch to Silver plating or Nickel plating and compare the dashed lines on the graph. Change to the steel spoon to see how a larger area gives a thinner coat, and use Start over to repeat.

Parameters you can change

  • Plating metal Copper (Cu²⁺), Silver (Ag⁺), Nickel (Ni²⁺)
  • Object to plate Steel key (15 cm²), Steel spoon (40 cm²)
  • Current I 0.1–2 A
  • Plating time 1–60 min

Questions to explore

  1. If you double the current or the plating time, how does the mass of copper deposited change?
  2. For the same charge, why does about 3.4 times more silver than copper deposit?
  3. With the same current and time, how much thinner is the coat on the spoon than on the key, and why?

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