Electroplating & Electrolysis Calculator
Calculate the mass of metal deposited during electrolysis using Faraday's laws. Used for electroplating, metal refining, and electrolytic cells.
Electrolysis and Faraday's Laws Guide
Faraday's Laws of Electrolysis
First law: the mass deposited is proportional to the charge passed. Second law: for the same charge, masses deposited are proportional to molar mass/charge number. Combined formula: m = (I × t × M) / (n × F). Where m = mass (g), I = current (A), t = time (s), M = molar mass (g/mol), n = number of electrons transferred per ion, F = Faraday constant (96,485 C/mol). Example: copper deposition (Cu²⁺ + 2e⁻ → Cu, n=2, M=63.5 g/mol) at 2A for 1 hour: m = (2 × 3600 × 63.5)/(2 × 96485) = 2.38g.
Electroplating Applications
Electroplating deposits a thin metal layer onto a conducting surface. The object to be plated is the cathode (negative electrode). The plating metal or an inert electrode is the anode. The electrolyte contains ions of the plating metal. Uses: chromium plating (decorative and corrosion protection), gold plating (electronics, jewellery), silver plating (cutlery), zinc galvanising (steel protection), copper interconnects in PCB manufacture. Thickness control: precisely calculated current × time con
Products of Electrolysis
At the cathode (reduction): positive ions gain electrons. Metals are deposited from metal salt solutions. From dilute H₂SO₄: H₂ gas produced (H⁺ + e⁻ → ½H₂). At the anode (oxidation): negative ions or water are oxidised. Chloride ions: Cl⁻ → ½Cl₂ + e⁻ (concentrated chloride). Sulphate ions in dilute H₂SO₄: water oxidised → O₂ + H⁺ + e⁻. Metal anodes dissolve: Cu → Cu²⁺ + 2e⁻ (used in copper refining where impure copper anode dissolves and pure copper deposits at cathode).
Electrolysis in Industry
Chlor-alkali industry: electrolysis of brine (NaCl solution) produces chlorine (Cl₂), hydrogen (H₂), and sodium hydroxide (NaOH). The Downs process: electrolysis of molten NaCl produces sodium metal and chlorine — the only commercial route to sodium metal. Aluminium production: electrolysis of aluminium oxide dissolved in cryolite — requires enormous electrical energy (approximately 14,000 kWh per tonne of aluminium — the reason aluminium recycling is so energy-efficient by comparison). Hydrogen
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