Electrolysis of Copper (ll) Sulfate Solution Using Copper Electrodes
In some electrolyses, the electrodes are not inert. They take part in the
electrolysis reactions and affect the ions that are discharged. This happens
if the anode is made of a metal such as copper or silver. An example is the
electrolysis of copper(ll) sulfate using copper electrodes (Figure 1.61).
The ions present are:
cations anions
From copper (ll) sulfuric: Cu2+(aq) SO42-(aq)
From water: H+(aq) OH-(aq)
At the cathode, as before, copper (ll) ions are discharged. Copper metal is deposited on the cathode:
Cu2+ (aq) + 2e- → Cu (s)
The copper anode affects what happens at the electrode. Neither the sulfate ions nor the hydroxide ions are discharged. Instead, the copper in the anode goes into the solution to form copper (ll) ions:
Cu (s) → Cu2+ (aq) + 2e-
The copper cathode gains copper and becomes larger. The copper anode dissolves and becomes smaller.
For each copper (ll) ion discharged at the cathode, one copper (ll) ion at the anode goes into the copper (ll) sulfate solution. Thus, the amount of
copper (ll) sulfate in the solution and the colour of the solution do not change.
Electrolysis of Copper (ll) Sulfate Solution Using Copper ElectrodesIn some electrolyses, the electrodes are not inert. They take part in theelectrolysis reactions and affect the ions that are discharged. This happensif the anode is made of a metal such as copper or silver. An example is theelectrolysis of copper(ll) sulfate using copper electrodes (Figure 1.61).The ions present are:cations anionsFrom copper (ll) sulfuric: Cu2+(aq) SO42-(aq) From water: H+(aq) OH-(aq) At the cathode, as before, copper (ll) ions are discharged. Copper metal is deposited on the cathode:Cu2+ (aq) + 2e- → Cu (s)The copper anode affects what happens at the electrode. Neither the sulfate ions nor the hydroxide ions are discharged. Instead, the copper in the anode goes into the solution to form copper (ll) ions:Cu (s) → Cu2+ (aq) + 2e-The copper cathode gains copper and becomes larger. The copper anode dissolves and becomes smaller.For each copper (ll) ion discharged at the cathode, one copper (ll) ion at the anode goes into the copper (ll) sulfate solution. Thus, the amount ofcopper (ll) sulfate in the solution and the colour of the solution do not change.
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