11.4.7. Activity 11.7

We will need copper sulphate and two copper plates of size around 10 cm × 4 cm. Take 250 mL of distilled water in a clean and dry beaker. Dissolve two teaspoonfuls of copper sulphate in it. Add a few drops of dilute sulphuric acid to copper sulphate solution to make it more conducting. Clean copper plates with sand paper. Now rinse them with water and dry them. Connect the copper plates to the terminals of a battery and immerse them in copper sulphate solution.

In this activity, you are preparing to demonstrate the process of electroplating, which involves depositing a layer of metal onto another object using electricity. To start, you need to create a solution by mixing copper sulphate in distilled water; this setup acts as a conductor of electricity when connected to a battery. The two cleaned copper plates will serve as electrodes, where one is connected to the positive terminal (anode) and the other to the negative terminal (cathode).

Think of electroplating like putting a shiny armor on a common warrior (the base metal). Just as a warrior may not be as impressive without armor, the base metal may not be attractive. By using electricity to ‘wear’ an outer layer of copper, the appearance is greatly enhanced without changing the base metal itself.

When electric current is passed through the copper sulphate solution, copper sulphate dissociates into copper and sulphate. The free copper gets drawn to the electrode connected to the negative terminal of the battery and gets deposited on it. But what about the loss of copper from the solution? From the other electrode, a copper plate, an equal amount of copper gets dissolved in the solution. Thus, the loss of copper from the solution is restored and the process continues.

During electroplating, an electric current causes the copper sulphate solution to break down into its components: copper ions and sulphate ions. The copper ions move towards the negatively charged electrode (cathode), where they gain electrons and are deposited as solid copper metal. Simultaneously, the copper from the positively charged electrode (anode) dissolves into the solution to maintain balance. This creates a continuous cycle that allows the electroplating to happen without depleting the solution.

Imagine this process as a dance: while some dancers (copper ions) join the main performance (the cathode), other dancers (copper metal from the anode) leave to allow for more room. This cycle keeps the dance floor full — or in this case, keeps the solution balanced with copper.

After doing the electroplating activity, Paheli interchanged the electrodes and repeated the activity. What do you think she would observe this time?

By switching the connections of the electrodes, the roles of the electrodes are reversed: what was previously the cathode becomes the anode and vice versa. This means that if Paheli now passes the current again, instead of copper being deposited on the previously negative electrode, it will be deposited on the previously positive electrode. This demonstrates that electroplating can be affected by the direction of the current flow and the connections made in the circuit.

Imagine switching roles in a classroom where a teacher (anode) usually instructs students and now becomes a student (cathode) following the teacher’s orders. This switch would result in a completely different dynamic and outcome in the learning environment, just as it does in the electroplating process.

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