Question

Heating rubber with sulphur is known as:
A) Galvanization
B) Bessemerisation
C) Vulcanization
D) Sulphonation

Answer 1

Hint: Natural rubber becomes soft at very high temperature hence, it is mixed with some ingredients such as sulphur to improve it and obtain desired physical properties. This process involves heating at a certain temperature hence the process name is related to the heating. One can analyse options given and relate them with the heating and make a correct choice.

Complete step by step answer:
1) The natural rubber becomes brittle at low-temperature below $283k$ and it becomes very soft at high temperatures at more than $335k$. It also has very high water absorption capacity.
2) Rubber is non-resistant to attack by other oxidizing agents and it is soluble in non-polar solvents. So, as to make changes in these properties and improvise the efficiency of rubber it is undergone through a process of heating with sulphur which is called a process of vulcanization.
3) The process of vulcanization consists of a mixture of raw rubber which is heated with sulphur at an appropriate temperature which ranges between $373k$ to $415k$. In the vulcanisation process, sulphur element forms a cross-link at the sites of double bonds which are reactive and make the rubber get stiffened.
Therefore, heating of rubber with sulphur is known as vulcanization which shows the option C as the correct choice.

Note:
The rubber is undergone through a process of vulcanization to improve its physical properties such as water repellent, resistance for oxidising agents and strength of rubber. One must not confuse that, the reaction is taken place with sulphur that doesn’t mean the process is sulphonation.