Electrolysis Calculator

Electrolysis is bookkeeping on electrons. Every ion discharged at an electrode consumes a fixed integer number of them, so the mass converted is set entirely by how much charge crossed the interface. Charge is current times time, Q = I times t, and dividing by the Faraday constant F = 96485 C/mol converts coulombs into moles of electrons, since F is simply the elementary charge multiplied by the Avogadro number. Dividing again by n, the electrons per ion, gives moles of product, and multiplying by molar mass gives grams: m = ItM/(nF). The value of n comes from the half-reaction, so silver from Ag+ takes n = 1, copper from Cu2+ takes n = 2, aluminium from Al3+ takes n = 3. One ampere for one hour delivers 3600 C, about 0.0373 mol of electrons, depositing roughly 1.19 g of copper. The mass figure is a theoretical ceiling. Current efficiency, the fraction of charge yielding the intended product, runs 90 to 98 percent in commercial plating and falls sharply when hydrogen evolution competes at the cathode. The energy figure is more distorted still: voltage times charge captures electrical input, but that voltage includes the decomposition potential plus activation overpotential at both electrodes plus ohmic drop. Hall-Heroult aluminium smelting illustrates the gap, consuming roughly 13 to 15 kWh per kilogram against a thermodynamic minimum near 6.3 kWh per kilogram. Temperature, electrode material, agitation, and current density all shift overpotential and energy, though none change the mass Faraday's law predicts.

Electrolysis appeared within weeks of the battery itself. After Alessandro Volta described his pile in 1800, William Nicholson and Anthony Carlisle in London passed its current through water that same year and collected hydrogen and oxygen at separate wires, the first demonstration that electricity could decompose a compound. Humphry Davy pushed the method to its limit at the Royal Institution, isolating potassium and sodium in 1807 by electrolysing molten hydroxides and adding calcium, strontium, barium, and magnesium the following year, expanding the list of known elements faster than any other single technique of the period. Michael Faraday, Davy's former assistant, supplied the quantitative laws between 1832 and 1834 in his Experimental Researches in Electricity, showing that deposited mass is proportional to charge and that equal charges liberate chemically equivalent masses of different substances. Working with the polymath William Whewell, he coined the vocabulary still in use, including electrode, anode, cathode, ion, and electrolyte. Industrial scale followed the invention of the dynamo: Charles Martin Hall in Ohio and Paul Heroult in France independently patented the molten-cryolite process for aluminium in 1886, turning a precious metal into a commodity, and Karl Josef Bayer's alumina process completed the chain in 1888. The Faraday constant itself became an exactly defined quantity in 2019, when the SI redefinition fixed the elementary charge and the Avogadro number.