Question

Write a short note on chrome plating.

Answer 1

Hint: Chrome plating is actually electroplating of chromium metal. We can use the basic principles of electrolysis using chromium metal and can complete chrome plating.

Complete answer:

Let’s see what chrome plating means.
The chrome plating process is a method in which we apply a thin layer of chromium metal onto a target material which could either be metal or an alloy by electroplating.

Method for chrome plating:
- Initially we need to clean the surface of the target material which will undergo chrome plating and make sure that no dirt or other impurities are present there.
- The contents of the cell for the electrolysis process are the same as other electrolysis processes. It includes two electrodes in which one electrode is made up of pure chromium metal which act as anode. The other electrode is made up of target metal or alloy on which plating is to be done which acts as a cathode. Both the electrodes are dipped into a solution containing chromium metal as we need the solution to be of the same metal.
- So, as we give external current, the pure chromium metal at anode gets oxidized and enters into solution, then it reaches a cathode where it reduces to its metallic form. So, as a result a thin layer of chromium metal is coated on the surface of the target metal. We can achieve different thickness of the layer of chromium metal by varying the current given.

Advantages and disadvantages:
- If chromic acid is used as a solution for electroplating, the process is also called hexavalent chrome plating and this is useful in preparing various types of decorative articles. Hexavalent form of chromium is the most toxic form of chromium metal hence its pollution must be avoided.
- Chrome plated automobile parts have more hardness and are more effective in daily usage.
- Trivalent chromium is a good alternative to hexavalent chromium which can be obtained from chromium sulfate solution. This form is not as toxic as hexavalent form so it is more advisable to use this type of chromium. Trivalent chromium plating is more costly than hexavalent chromium plating.

Note:
Remember that oxidation always occurs at the anode and reduction always occurs at cathode in the electrolysis as well. Do not mean that as galvanic cell process and electrolysis are exactly inverse of each other, the reactions will also occur inversely.