Question

electrodes. Copper from impure rod is sought to be transfered to the thin
The process that you saw in Activity 14.7 is used for purification of copper.
A thin plate of pure copper and a thick rod of Impure copper are used as
plate. Which electrode should be attached to the positive terminal
copper
of the battery and why?​

Answer 1

Purification of Copper by Electrolysis:

1. Copper is purified by Electrolysis.

2. Materials required are:

• Copper sulphate (CuSO₄) solution as Electrolyte
• Thin pure Copper as Cathode →

Negative Electrode connected to -ve terminal of Battery

• Thick Impure Copper as Anode →

Positive Electrode connected to +ve terminal of Battery.

• Battery

3.  Above materials are connected and Current is passed through them with the help of a Battery.

4. When Electricity is passed through the above set-up:

• Anode (Thick Impure Copper) loses mass as Copper dissolves into the Electrolyte.

Oxidation Reaction:  $\bf{Cu \longrightarrow Cu ^{2+} + 2 e ^{-}}$

• Cathode (Thin Pure Copper) gains mass as dissolved Copper gets deposited on it.

Reduction Reaction: $\bf {Cu^{2+} + 2 e^{-} \longrightarrow Cu}$

5. At the Anode → Electrons are lost. So, It is called 'Oxidation Reaction.'

At the Cathode → Electrons are gained. So, It is called 'Reduction Reaction.'

→ Thus Pure Copper gets deposited on the Cathode.

Answer 2

Answer:

The thick rod of impure copper plate is to be attached to the positive terminal of the battery because when electric current is passed through the copper sulphate solution, it gets dissociated into copper and sulphate. The free copper, being positively charged, gets drawn to the negative terminal of the battery and gets deposited on it. On the other hand the loss of copper from the solution is regained from the impure copper rod which is attached to the positive terminal of the battery.