Question

Bakelite is the product of the reaction between
A) Formaldehyde and NaOH
B) Aniline and Urea
C) Phenol and Methanal
D) Phenol and chloroform

Answer 1

Hint: We have to remember that the copolymers is a polymer made up of two or more monomeric units. For example commonly used copolymers are polyethylene-vinyl acetate which is used in car covers, cosmetic bags etc,. Nitrile rubber which is obtained by copolymerization of acrylonitrile and butadiene, it is used in gaskets, synthetic leather etc.

Complete step by step answer:
We have to remember that there are many copolymers which are very useful for us. Among them one of the important copolymers is Bakelite. The commercial name of polyoxybenzylmethylenglycolanhydride is Bakelite and the chemical formula of Bakelite is ${\left( {{C_6}{H_6}O - C{H_2}OH} \right)_n}$ . It is made up of copolymerization of n times of phenol and n times of methanal (formaldehyde).
$n{\text{ Phenol + n Methanal(formaldehyde)}} \to {\text{Bakelite}}$

Now let us see how Bakelite is made, the condensation copolymer of formaldehyde and phenol in controlled acidic or basic medium at high temperature in the presence of catalyst gives Bakelite, the catalyst used here are Zinc chloride or HCl or $NH_3$. Depending upon the concentration of phenol and formaldehyde the medium of the reaction occurs, like when phenol concentration is higher than formaldehyde then the reaction takes place in acidic medium, and the product formed is Novolac . When the concentration of the aldehyde is more than phenol then reaction occurs in the basic medium and the product obtained is Resol. Both the products are used in industries. Now, Novolac undergoes cross linking with cross linking agents like acids alcohols or formaldehyde, here since phenol is in excess amount it is used as the cross linking agent.

Therefore, the option C is correct.

Note: Now let us see the properties of Bakelite as,
It is low in conductivity and high in heat resistance.
It is easily molded to give perfect shape.
It is resistant to several destructive solvents.
Now let us see the uses of Bakelite, since it is low in electrical conductivity and high in heat resistant it is used in switches. It is also used in utensils etc,. it is used as a binding agent. They are also used for protective purposes and in coating industries.