Chapter 15 Polymers Solutions
Question - 1 : - What are polymers?
Answer - 1 : -
Polymers are high molecular massmacromolecules, which consist of repeating structural units derived frommonomers. Polymers have a high molecular mass (103 −107 u). In a polymer, various monomer units arejoined by strong covalent bonds. These polymers can be natural as well assynthetic. Polythene, rubber, and nylon 6, 6 are examples of polymers.
Question - 2 : - How are polymers classified on the basis of structure?
Answer - 2 : -
Polymers are classified on the basis of structure asfollows:
1. Linearpolymers:
These polymers are formed of long straight chains. Theycan be depicted as:
For e.g., high density polythene (HDP), polyvinylchloride, etc.
2. Branched chainpolymers:
These polymers are basically linear chain polymers withsome branches. These polymers are represented as:
For e.g., low density polythene (LDP), amylopectin, etc.
3. Cross-linked orNetwork polymers:
These polymers have many cross-linking bonds that giverise to a network-like structure. These polymers contain bi-functional andtri-functional monomers and strong covalent bonds between various linearpolymer chains. Examples of such polymers include bakelite and melmac.
Question - 3 : - Classify the following as addition and condensationpolymers: Terylene, Bakelite, Polyvinyl chloride, Polythene.
Answer - 3 : -
Addition polymers:
Polyvinyl chloride, polythene
Condensation polymers:
Terylene, bakelite
Question - 4 : - Write the names of monomers of the following polymers:
Answer - 4 : - 
Answer
(i) Hexamethylenediamine 
and adipic acid (ii)
(iii) Tetrafluoroethene 
Explain the difference between Buna-N and Buna-S.
Answer - 5 : -
Buna − N is a copolymer of 1, 3−butadiene andacrylonitrile.
Buna − S is a copolymer of 1, 3−butadiene and styrene.
Question - 6 : - Arrange the following polymers in increasing order oftheir intermolecular forces.
Answer - 6 : -
(i) Nylon 6, 6, Buna-S, Polythene.
(ii) Nylon 6, Neoprene, Polyvinyl chloride.
Answer
Different types of polymers have different intermolecularforces of attraction. Elastomers or rubbers have the weakest while fibres havethe strongest intermolecular forces of attraction. Plastics have intermediateintermolecular forces of attraction. Hence, the increasing order of theintermolecular forces of the given polymers is as follows:
(i) Buna − S < polythene < Nylon 6, 6
(ii) Neoprene < polyvinyl chloride < Nylon 6
Question - 7 : - Explain the terms polymer and monomer.
Answer - 7 : -
Polymers are high molecular massmacromolecules composed of repeating structural units derived from monomers.Polymers have a high molecular mass (103 − 107 u).In a polymer, various monomer units are joined by strong covalent bonds.Polymers can be natural as well as synthetic. Polythene, rubber, and nylon 6, 6are examples of polymers.
Monomers are simple, reactive molecules that combine witheach other in large numbers through covalent bonds to give rise to polymers.For example, ethene, propene, styrene, vinyl chloride.
Question - 8 : - What are natural and synthetic polymers? Give two examplesof each type.
Answer - 8 : -
Natural polymers are polymers that are found in nature.They are formed by plants and animals. Examples include protein, cellulose,starch, etc.
Synthetic polymers are polymers made by human beings.Examples include plastic (polythene), synthetic fibres (nylon 6, 6), syntheticrubbers (Buna − S).
Question - 9 : - Distinguish between the terms homopolymer and copolymerand give an example of each.
Answer - 9 : -
| Homopolymer | Copolymer |
| The polymers that are formed by the polymerization of a single monomer are known as homopolymers. In other words, the repeating units of homopolymers are derived only from one monomer. For example, polythene is a homopolymer of ethene. | The polymers whose repeating units are derived from two types of monomers are known as copolymers. For example, Buna−S is a copolymer of 1, 3-butadiene and styrene. |
Question - 10 : - How do you explain the functionality of a monomer?
Answer - 10 : -
The functionality of a monomer is the number of bindingsites that is/are present in that monomer.
For example, the functionality of monomers such asethene and propene is one and that of 1, 3-butadiene and adipic acid is two.