Assertion :Blue colour of aq. CuSO4 turns almost colourless on its electrolysis using Pt electrodes. Reason: The copper ions are converted to the copper deposit on the cathode.
Assertion :Blue colour of aq. CuSO4 turns almost colourless on its electrolysis using Pt electrodes. Reason: The copper ions are converted to the copper deposit on the cathode.
The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
The half-equations for the electrolysis of copper(II) sulfate solution
The negative cathode reaction with graphite electrodes
The negative cathode electrode attracts Cu2+ ions (from copper sulfate) and H+ ions (from water). Only the copper ion is discharged, being reduced to copper metal. The less reactive a metal, the more readily its ion is reduced on the electrode surface.
A copper deposit forms as the positive copper ions are attracted to the negative electrode (cathode)
Cu2+(aq)+2e→Cu(s)
positive ion reduction by electron gain
The blue colour of the copper ion will fade as the copper ions are converted to the copper deposit on the cathode.
The positive anode reaction with graphite electrodes
Oxygen gas is formed at the positive electrode, an oxidation reaction (electron loss).
The negative sulphate ions (SO2−4) or the traces of hydroxide ions (OH−) are attracted to the positive electrode. But the sulfate ion is too stable and nothing happens. Instead either hydroxide ions or water molecules are discharged and oxidised to form oxygen.
4OH−(aq)+4e−→2H2O(l)+O2(g)
negative ion oxidation by electron loss
The half-equations for the electrolysis of copper(II) sulfate solution
The negative cathode reaction with graphite electrodes
The negative cathode electrode attracts Cu2+ ions (from copper sulfate) and H+ ions (from water). Only the copper ion is discharged, being reduced to copper metal. The less reactive a metal, the more readily its ion is reduced on the electrode surface.
A copper deposit forms as the positive copper ions are attracted to the negative electrode (cathode)
Cu2+(aq)+2e→Cu(s)
positive ion reduction by electron gain
The blue colour of the copper ion will fade as the copper ions are converted to the copper deposit on the cathode.
The positive anode reaction with graphite electrodes
Oxygen gas is formed at the positive electrode, an oxidation reaction (electron loss).
The negative sulphate ions (SO2−4) or the traces of hydroxide ions (OH−) are attracted to the positive electrode. But the sulfate ion is too stable and nothing happens. Instead either hydroxide ions or water molecules are discharged and oxidised to form oxygen.
4OH−(aq)+4e−→2H2O(l)+O2(g)
negative ion oxidation by electron loss
