Question

NCERT VIII - Sciences

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 electrodes. Copper from impure rod is sought to be transferred to the thin copper plate. Which electrode should be attached to the positive terminal of the battery and why?

Answer 1

Electrode of impure copper is connected with the negative terminal. 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.

Answer 2

Negative terminal should be connected to impure rod, while positive terminal to pure copper rod.

•The process referred to here is electroplating.

•Electroplating is a technique in which electricity or current splits the ions, to be made available for coating on impure material.

•Impure rod is connected to negative terminal, because copper ions are present in salt solution.

•They are positively charged, so they are attracted towards negative terminal of impure rod, thus coating is done.

•Pure copper rod is connected to positive terminal, to release the electrons, to reduce pure copper.