Electrolytic Cells and Electrolysis

Electrolytic Cells and Electrolysis

Electrolytic Cells and Electrolysis

Electrolysis is a process of passing a direct current through the electrodes to achieve a chemical reaction. It is not possible to achieve a chemical reaction when the chosen electrolyte is in a solid-state. Aqua regia also known as royal water is a yellow-orange mixture of concentrated nitric acid and hydrochloric acid in the ratio 1:3. It is used by an alchemist to dissolve noble metals like gold and silver.

Electrodes which do not take part in the chemical reaction during electrolysis are known as inert electrodes. Gold, silver and graphite do not take part in the process, but graphite is preferred because gold and silver electrodes are expensive. Electrolytic Cells and Electrolysis In the electrolysis of NaCl, if the electrolyte is molten NaCl, then the only ions formed after dissociation are Na+ and Cl– ions. The cathode being a negatively charged electrode attracts the positive Na+ ions and neutralizes it to form Sodium metal.

Na2SO4 dissociates into Na+ and SO42- ions in the electrolysis of aqueous Na2SO4. Na+ has much lower reduction potential than water and hence Na+ ions are not reduced at the cathode. Instead, reduction of water occurs giving out hydrogen gas at the cathode.

In the electrolysis of aqueous CuSO4, Cu2+, SO42+, H+ and OH– are the ions formed after dissociation. Copper ions have much higher reduction potential than water. Hence, these ions are easily reduced and deposited as Cu at the cathode. Electroplating is a process that uses direct electric current to carry metal ions from anode and carry them through the electrolyte containing the metal ion to the cathode to get a coherent metal coating.

The electrolyte in electrolysis should contain the metal to be coated, gold in this case. AuCN is used because it is exceptionally stable and doesn’t resist the flow of Au+ ions from anode to cathode.

The two electrodes that are used in a Daniell cell are zinc (as anode) and copper (as cathode) electrodes which are dipped in a solution containing its own ions, generally zinc sulphate and copper sulphate.

Yes, the distance between the electrodes is directly proportional to the resistance between them. As the distance between the two electrodes increases, the resistance offered by the electrolyte increases and therefore reduces the voltage between them.

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