Name: Electrolysis
Uploaded: 2019-07-19
Duration: 5 min 50 s
Description: When an electric current is passed through an electrolytic solution, it brings about a chemical reaction. Let’s discuss the principle behind this phenomenon!

Question

Compare the electrolysis of molten potassium chloride and solution of potassium chloride. What are the processes taking place at the cathode and the anode?

Accepted Answer

During electrolysis, one electrode is connected to positive terminal of battery (anode) and other electrode to the negative terminal (cathode). At anode oxidation takes place and at cathode reduction takes place.

Electrolysis of molten potassium chloride: In molten potassium chloride, positively charged potassium ions and negatively charged chloride ions are free to move.

Electrolysis of solution of potassium chloride: In solution of potassium chloride, ions of potassium, chloride, hydronium, hydroxide and water are present which move freely.

Electrolysis of molten potassium chloride: $KCl \to K^{+} + {Cl}^{-}$

At anode: $2 {Cl}^{-} \to {Cl}_{2 (g)} + 2 e^{-}$

At cathode: $2 K^{+} + 2 e^{-} \to 2 K$

Electrolysis of solution of potassium chloride:

$KCl \to K^{+} + {Cl}^{-} H_{2} O \to H^{+} + {OH}^{-} H_{2} O + H^{+} \to H_{3} O^{+}$

Positive ions, i.e, potassium and hydronium go to the cathode, but water has greater tendency to get reduced.

At anode: $2 {Cl}^{-} \to {Cl}_{2 (g)} + 2 e^{-}$

At cathode: $2 H_{2} O + 2 e^{-} \to H_{2} + {OH}^{-}$

Compare the electrolysis of molten potassium chloride and solution of potassium chloride. What are the processes taking place at the cathode and the anode?

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