Question

The s-block element used as a catalyst in the manufacture of Buna-S rubber is:
a.) Mg
b.) Ca
c.) Ba
d.) Na

Answer 1

Hint: To answer the name of the correct catalyst, we should first know about the manufacturing process of Buna-S. The answer of this question is a soft, silvery-white, highly reactive metal.


Complete step by step solution:
 Let us know about the manufacturing process of Buna-S rubber. We should know that Buna-S rubber is one of the commonly used synthetic rubbers. It should be noted that it is a random co-polymer formed by the emulsion polymerisation of a mixture of 1:3 butadiene and styrene. So, we can call 1.3-butadiene and styrene as the monomers of Buna-S. We should know that the styrene/butadiene ratio influences the properties of the polymer: with high styrene content, the rubbers are harder and less rubbery.
We should note that n Buna-S, Bu stands for butadiene and, Na for sodium and S for styrene. It is vulcanised with sulphur. Let us now observe the reaction:
The above reaction is

The above reaction is the conversion of 1,3-Butadiene and styrene into Buna S or we can say that it is Butadiene-Styrene Copolymer. As we can see in the reaction, sodium is used for this conversion. So, from the above discussion we can say that the S block element which is used as a catalyst in the manufacture of Buna-S is sodium or Na. The correct answer of this question is option D that is Na.

Note: Now, we will know about the use of Buna-S. We should note that it is used for the manufacture of passenger car tyres and treads, motorcycle and scooter tyres, cycle tyres and tubes. They are also used for the manufacture of conveyor belts, foot-wares, shoe soles, hoses and electrical insulation.