In an illuminating experiment suitable for secondary school students, a Hoffman electrolysis apparatus is employed to determine the fundamental electronic charge. The volume and pressure of hydrogen gas produced via the electrolysis of water during a given time interval are measured. Utilizing the ideal gas law and basic stoichiometric proportions, this volume is shown to be directly proportional to the electron moles necessary to reduce that quantity of hydrogen. Measurements of the current output of the low voltage source powering the electrolysis and the duration of the current flow allow for the calculation of the electric charge of a single electron. Pedagogically, this activity interrelates the studies of electrochemistry, gases, and stoichiometry in an efficient laboratory activity.
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