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In the electrolysis of aqueous solutions , what products can form at the cathode?

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VeldaMaster · Tutor for 5 years

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During electrolysis, hydrogen gas usually forms at the cathode. Alternatively, if the electrolyte contains metal ions that are less reactive than hydrogen, the metal may be deposited at the cathode too.

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During electrolysis, there are two possible reactions that can occur at the cathode, depending on the concentration of the electrolyte and the type of cathode used. 1. Hydrogen gas can be formed if the solution is highly concentrated or if an inert cathode, typically made of graphite or platinum, is used. The hydrogen ions from the water are discharged (since they are preferentially selected over the ions from the salt). These ions accept electrons from the cathode and are then converted to hydrogen gas. This is illustrated in the following half-equation: \[2H^{+}(aq) + 2e^{-} → H_{2}(g)\] 2. Alternatively, a metal can be deposited onto the cathode, if the solution of the electrolyte contains metal ions that are less reactive than hydrogen. Using a copper solution as an example, the half-equation would be: \[ Cu^{2+}(aq) + 2e^{-} → Cu(s) \] In dilute solutions, the discharge of hydroxide ions are highly possible, however, usually it happens under factory conditions, so in realistic conditions for standard electrochemical series, you could see Hydrogen and metals (less reactive than Hydrogen deposits):

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In the electrolysis of aqueous solutions , what products can form at the cathode?

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