Intermediate Topic 574 of 1102 Acids, Bases & Electrochemistry
Electroplating
Coating an object with a metal layer by electrolysis.
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In-depth explanation of Electroplating
In electroplating the object to be coated is made the cathode of an electrolytic cell containing a solution of the coating metal's ions, and the anode is usually made of the plating metal so that it dissolves to replenish the solution. Passing a controlled direct current deposits a thin, adherent layer whose thickness depends on the charge passed, as given by Faraday's laws. Plating improves the corrosion resistance, appearance, hardness or conductivity of a surface. The process must be carefully controlled to give uniform coatings, and solution composition and current density strongly affect quality. Electroplating is a major industry in automotive and jewelry manufacturing.
Going deeper: Electroplating
Key ideas: Object is the cathode, plating metal is usually the anode, and the electrolyte contains ions of the plating metal. Thickness = mass/(density x area). Smooth deposits need low current density, controlled pH, additives and often a complexing bath such as cyanide silver. Typical use: Cr, Ni, Zn, Ag, Au.
Common mistakes and connections: Mistakes: connecting the object to the positive terminal (it would dissolve), forgetting the area when computing thickness, and expecting 100 percent efficiency (hydrogen evolution lowers it, especially for chrome). Too high current gives rough, powdery deposit. Quantities follow Faraday first law.
Visualization of Electroplating
In electroplating the object is the cathode and the plating metal the anode, so metal dissolves at one electrode and deposits as a thin layer on the other. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Chromium plating gives car trim a hard, bright, corrosion-resistant surface on a steel base.
Frequently asked questions about Electroplating
What is Electroplating?
Coating an object with a metal layer by electrolysis.
Is Electroplating a beginner, intermediate or advanced topic?
Electroplating is a intermediate topic in Acids, Bases & Electrochemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Electroplating?
Study these earlier topics in Acids, Bases & Electrochemistry first: Faraday's Second Law, Electrolysis of Molten Salts, Electrolysis of Aqueous Solutions.
What comes after Electroplating?
The next topics in Acids, Bases & Electrochemistry are Electrorefining and Hall-Heroult Process.
Can I practise Electroplating with quizzes?
Yes. The interactive lesson includes a self-check question on Electroplating, and the Acids, Bases & Electrochemistry quiz draws on every topic in this area.
Where Electroplating fits in Acids, Bases & Electrochemistry
Electroplating is topic 64 of 105 in Acids, Bases & Electrochemistry.