Question

12. The process that you saw in Activity 8.7 is used for purification of copper. A thin plate of pure
copper and a thick rod of impure copper are used as electrodes. Copper from impure rod is
sought to be transfered to the thin copper plate. Which electrode should be attached to the
positive terminal of battery and why? ki​

Answer 1

Answer:

Explanation:

Because pure copper metal, which is positively charged, from positive terminal is deposited over the negative terminal of thin copper after dissolving in the solution. Negative terminal should be connected to impure rod, while positive terminal to pure copper rod. The process referred to here is electroplating

Answer 2

Answer:

Impure copper rod should be attached to the positive terminal of the battery.

Before explaining the reason behind it, let's know some important terms:

Important terms:

Ions - Positively or negatively charged atoms. (They gain positive charge by giving or losing electrons and negative charge by taking electrons)

Cations - Positively charged ions. Usually metals form cations.

Anions - Negatively charged ions. Non metals forms anions.

Cathode - Negative electrode

Anode - Positive electrode

Now, let's understand why the impure copper rod will be attached to the positive terminal of the battery.

Explanation:

As copper is a metal, it forms the positively charged ions called cations. The positively charged ions (cations) go and get attracted towards the negative electrode (cathode). The copper ions from the impure copper rod will go and dissolve in the copper sulphate solution. As already mentioned, copper forms cations, the copper ions will go and get attracted towards the negative electrode pure copper plate (cathode). Therefore we will always see the copper deposit on the pure copper plate only. The impurities present just beneath the impure copper rod is termed as anode mud.

To sum up, we can say that, impure copper rod should be connected to positive terminal of the battery (anode) and pure copper plate should be connected to negative terminal of the battery (cathode).