Question

During the purification of copper by electrolysis:
A. The anode used is made of copper ore.
B. Pure copper is deposited on the cathode
C. The impurities such as ${{Ag,Au}}$ present in solutions as ions
D. Concentration of ${{CuS}}{{{O}}_4}$ solution remains constant during dissolution of ${{Cu}}$.

Answer 1

Hint:The major ores of copper are copper pyrite, chalcocite, malachite green, azurite blue, bornite and cuprite. Blister is the impure form of copper. But this copper is $99\% $ pure. Blister copper is purified or refined using the method electrolysis.

Complete step by step answer:
Blister copper has several impurities like iron, arsenic, zinc, lead, gold and silver. It is refined using an electrolysis method. Using this method, pure copper is obtained. Blister copper acts as an anode and pure copper acts as cathode.
During electrolysis method, current is passed through a solution of copper, i.e. copper sulfate solution. There are two electrodes-positive and negative electrodes. The positive electrode is called anode and the negative electrode is called the cathode. In this method ionic compounds get dissociated.
The reaction which occurs at anode is given below:
${{Cu}} \to {{C}}{{{u}}^{2 + }} + 2{{{e}}^ - }$
Here, the oxidation occurs.
While the reaction which occurs at cathode is given below:
${{C}}{{{u}}^{2 + }} + 2{{{e}}^ - } \to {{Cu}}$
Here, reduction occurs.
Some ${{C}}{{{u}}^{2 + }}$ ions are lost from anode which is gained by cathode. Thus the pure copper is obtained. When each copper ion is deposited at a cathode, some ions move into solution at anode. But concentration will remain constant.
The impurities in the blister copper like iron, nickel, zinc are dissolved in the solution and gold, silver and platinum deposits below the anode as anode mud.

Hence, options A,B and D are correct.

Note:
Since the anode is impure copper and cathode is pure copper, electrons are moved from anode to cathode. Also, the mass of anode is decreased because the amount of impure copper is decreasing. The mass of cathode is increased since the amount of pure copper is increasing.