Request a Free Counselling Session from our Expert Mentor

Get Free NCERT Solutions for Class 12 Chemistry Chapter 15 Polymers, set up after careful examination by profoundly experienced Chemistry instructors, at Swastik Classes. NCERT Solutions are extremely helpful while doing your homework and also for your Class 12 board exam preparation. We have given bit-by-bit answers to every one of the questions given in the NCERT class 12 Chemistry course reading. This solution is free to download and the questions are systematically arranged for your ease of preparation and in solving different types of questions. To score good marks, students are encouraged to get familiar with these NCERT solutions of Chapter 15 Polymers.

Download PDF of NCERT Solutions for Class 12 Chemistry Chapter 15 Polymers

Answers of Chemistry NCERT solutions for class 12 Chemistry Chapter 15 Polymers

Chapter 15

Polymers

Intext Questions 

Question 15.1:

What are polymers?

Answer:

Polymers are high molecular mass macromolecules, which consist of repeating structural units derived from monomers. Polymers have high molecular mass (103 − 107 u). In a polymer, various monomer units are joined by strong covalent bonds. These polymers can be natural as well as synthetic. Polythene, rubber, and nylon 6, 6 are examples of polymers.

Question 15.2:

How are polymers classified on the basis of structure?

Answer:

Polymers are classified on the basis of structure as follows:

1. Linear polymers:

These polymers are formed of long straight chains. They can be depicted as:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5731/NS(INTEXT)_12-11-08_Utpal_12_Chemistry_15_6_html_m6fb5098c.jpg

For e.g., high density polythene (HDP), polyvinyl chloride, etc.

2. Branched chain polymers:

These polymers are basically linear chain polymers with some branches. These polymers are represented as:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5731/NS(INTEXT)_12-11-08_Utpal_12_Chemistry_15_6_html_m6ba3403e.jpg

For e.g., low density polythene (LDP), amylopectin, etc.

3. Cross-linked or Network polymers:

These polymers have many cross-linking bonds that give rise to a network-like structure. These polymers contain bi-functional and tri- functional monomers and strong covalent bonds between various linear polymer chains. Examples of such polymers include bakelite.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5731/NS(INTEXT)_12-11-08_Utpal_12_Chemistry_15_6_html_m1471f0b2.jpg

Question 15.3:

Write the names of monomers of the following polymers:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5732/NS(INTEXT)_12-11-08_Utpal_12_Chemistry_15_6_html_671d0ae3.jpg

Answer:

(i)  Hexamethylenediamine andadipic acid 

(ii)

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5732/NS(INTEXT)_12-11-08_Utpal_12_Chemistry_15_6_html_58bf7fa6.jpg

(iii)  Tetrafluoroethene CF2 = CF2

Question 15.4:

Classify the following as addition and condensation polymers: Terylene, Bakelite, Polyvinyl chloride, Polythene.

Answer:

Addition polymers:

Polyvinyl chloride, polythene

Condensation polymers:

Terylene, bakelite

Question 15.5:

Explain the difference between Buna-N and Buna-S.

Answer:

Buna − N is a copolymer of 1, 3−butadiene and acrylonitrile.

Buna − S is a copolymer of 1, 3−butadiene and styrene.

Question 15.6:

Arrange the following polymers in increasing order of their intermolecular forces.

(i)  Nylon 6, 6, Buna-S, Polythene.

(ii)  Nylon 6, Neoprene, Polyvinyl chloride.

Answer:

Different types of polymers have different intermolecular forces of attraction. Elastomers or rubbers have the weakest while fibres have the strongest intermolecular forces of attraction. Plastics have intermediate intermolecular forces of attraction. Hence, the increasing order of the intermolecular forces of the given polymers is as follows:

(i)  Buna − S < polythene < Nylon 6, 6

(ii)  Neoprene < polyvinyl chloride < Nylon 6

Exercises

Question 15.1:

Explain the terms polymer and monomer.

Answer:

Polymers are high molecular mass macromolecules 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, 6 are examples of polymers.

Monomers are simple, reactive molecules that combine with each other in large numbers through covalent bonds to give rise to polymers. For example, ethene, propene, styrene, vinyl chloride.

Question 15.2:

What are natural and synthetic polymers? Give two examples of each type.

Answer:

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), synthetic rubbers (Buna − S).

*Question 15.3:

Distinguish between the terms homopolymer and copolymer and give an example of each.

Answer:

HomopolymerCopolymer
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 15.4:

How do you explain the functionality of a monomer?

Answer:

The functionality of a monomer is the number of binding sites that is/are present in that monomer.

For example, the functionality of monomers such as ethene and propene is one and that of 1, 3-butadiene and adipic acid is two.

Question 15.5:

Define the term polymerisation.

Answer:

Polymerization is the process of forming high molecular mass (103 − 107 u) macromolecules, which consist of repeating structural units derived from monomers. In a polymer, various monomer units are joined by strong covalent bonds.

*Question 15.6:

Is https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5741/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m5db8ad43.jpg, a homopolymer or copolymer?

Answer:

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5741/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m5db8ad43.jpg is a homopolymer because it is obtained from a single monomer unit, NH2−CHR−COOH.

Question 15.7:

In which classes, the polymers are classified on the basis of molecular forces?

Answer:

On the basis of magnitude of intermolecular forces present in polymers, they are classified into the following groups:

(i)  Elastomers

(ii)  Fibres

(iii)  Thermoplastic polymers

(iv)  Thermosetting polymers

*Question 15.8:

How can you differentiate between addition and condensation polymerisation?

Answer:

Addition polymerization is the process of repeated addition of monomers, possessing double or triple bonds to form polymers. For example, polythene is formed by addition polymerization of ethene.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5743/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m24c82cda.jpg

Condensation polymerization is the process of formation of polymers by repeated condensation reactions between two different bi-functional or tri-functional monomers. A small molecule such as water or hydrochloric acid is eliminated in each condensation. For example, Nylon 6, 6 is formed by condensation polymerization of hexamethylenediamine and adipic acid.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5743/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m33870684.jpg

Question 15.9:

Explain the term copolymerisation and give two examples.

Answer:

The process of forming polymers from two or more different monomeric units is called copolymerization. Multiple units of each monomer are present in a copolymer. The process of forming polymer Buna−S from 1, 3-butadiene and styrene is an example of co-polymerization

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5744/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m494be484.jpg

Nylon 6, 6 is also a copolymer formed by hexamethylenediamine and adipic acid.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5744/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m35660f99.jpg

*Question 15.10:

Write the free radical mechanism for the polymerisation of ethene.

Answer:

Polymerization of ethene to polythene consists of heating or exposing to light a mixture of ethene with a small amount of benzoyl peroxide as the initiator.

The reaction involved in this process is given below:

https://img-nm.mnimgs.com/img/study_content/content_ck_images/images/93548_a(1).png
https://img-nm.mnimgs.com/img/study_content/content_ck_images/images/96548_b(1).png

Question 15.11:

Define thermoplastics and thermosetting polymers with two examples of each.

Answer:

Thermoplastic polymers are linear (slightly branched) long chain polymers, which can be repeatedly softened and hardened on heating. Hence, they can be modified again and again. Examples include polythene, polystyrene.

Thermosetting polymers are cross-linked or heavily branched polymers which get hardened during the molding process. These plastics cannot be softened again on heating. Examples of thermosetting plastics include bakelite, urea-formaldehyde resins.

Question 15.12:

Write the monomers used for getting the following polymers.

(i)  Polyvinyl chloride  (ii)  Teflon  (iii)  Bakelite

Answer:

(i)  Vinyl chloride (CH2=CHCl)

(ii)  Tetrafluoroethylene (CF2 = CF2)

(iii) Formaldehyde (HCHO) and phenol (C6H5OH)

Question 15.13:

Write the name and structure of one of the common initiators used in free

radical addition polymerisation.

Answer:

One common initiator used in free radical addition polymerization is benzoyl peroxide. Its structure is given below.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5748/NS_12-11-08_Utpal_12_Chemistry_15_20_html_mb0c2cac.jpg

Question 15.14:

How does the presence of double bonds in rubber molecules influence their

structure and reactivity?

Answer:

Natural rubber is a linear cis-polyisoprene in which the double bonds are present between C2 and C3 of the isoprene units.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5749/NS_12-11-08_Utpal_12_Chemistry_15_20_html_f7279f9.jpg

Because of this cis-configuration, intermolecular interactions between the various strands of isoprene are quite weak. As a result, various strands in natural rubber are arranged randomly. Hence, it shows elasticity.

*Question 15.15:

Discuss the main purpose of vulcanisation of rubber.

Answer:

Natural rubber though useful has some problems associated with its use. These limitations are discussed below:

1.  Natural rubber is quite soft and sticky at room temperature. At elevated temperatures (> 335 K), it becomes even softer. At low temperatures (< 283 K), it becomes brittle. Thus, to maintain its elasticity, natural rubber is generally used in the temperature range of 283 K-335 K.

2.  It has the capacity to absorb large amounts of water.

3.  It has low tensile strength and low resistance to abrasion.

4.  It is soluble in non-polar solvents.

5.  It is easily attacked by oxidizing agents.

Vulcanization of natural rubber is done to improve upon all these properties. In this process, a mixture of raw rubber with sulphur and appropriate additive is heated at a temperature range between 373 K and 415 K.

Question 15.16:

What are the monomeric repeating units of Nylon-6 and Nylon-6, 6?

Answer:

The monomeric repeating unit of nylon 6 is which is derived from Caprolactam.

The monomeric repeating unit of nylon 6, 6 ishttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5751/NS_12-11-08_Utpal_12_Chemistry_15_20_html_5a0f768f.gif

which is derived from hexamethylene diamine and adipic acid.

*Question 15.17:

Write the names and structures of the monomers of the following polymers:

(i)  Buna-S  (ii) Buna-N

(iii)  Dacron  (iv)  Neoprene

Answer:

Sr. No.PolymerMonomerStructure of monomer
iBuna-S1, 3-butadienehttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5752/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m7464feb.gif
Styrenehttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5752/NS_12-11-08_Utpal_12_Chemistry_15_20_html_21b34795.gif
iiBuna-N1, 3-butadienehttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5752/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m7464feb.gif
Acrylonitrilehttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5752/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m4e5cd0c1.gif
iiiNeopreneChloroprenehttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5752/NS_12-11-08_Utpal_12_Chemistry_15_20_html_4056d86a.jpg
ivDacronEthylene glycolhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5752/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m772956cf.gif
Terephthalic acidhttps://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5752/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m3cc0b957.jpg

Question 15.18:

Identify the monomer in the following polymeric structures.

(i)

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5753/NS_12-11-08_Utpal_12_Chemistry_15_20_html_c8dadca.jpg

(ii)

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5753/NS_12-11-08_Utpal_12_Chemistry_15_20_html_me40870a.jpg

Answer:

(i)  The monomers of the given polymeric structure are decanoic acid and hexamethylene diamine

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5753/NS_12-11-08_Utpal_12_Chemistry_15_20_html_78c87b06.gif https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5753/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m58a4eac6.gif.

(ii)  The monomers of the given polymeric structure are

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5753/NS_12-11-08_Utpal_12_Chemistry_15_20_html_m3cc319c6.jpg

Question 15.19:

How is dacron obtained from ethylene glycol and terephthalic acid?

Answer:

The condensation polymerisation of ethylene glycol and terephthalic acid leads to the formation of dacron.

https://img-nm.mnimgs.com/img/study_content/editlive_ncert/77/2012_04_05_14_44_30/470.png

*Question 15.20:

What is a biodegradable polymer? Give an example of a biodegradable aliphatic polyester.

Answer:

A polymer that can be decomposed by bacteria is called a biodegradable polymer.

Poly-β-hydroxybutyrate-CO-β- hydroxyvalerate (PHBV) is a biodegradable aliphatic polyester.

https://img-nm.mnimgs.com/img/study_content/curr/1/12/17/274/5755/NS_12-11-08_Utpal_12_Chemistry_15_20_html_4bd4ea3b.jpg

Class 12 NCERT Solutions Chapter 15 – Polymers

NCERT Solutions for Class 12 Chemistry Chapter 15 includes the topics – the terms Monomer, Polymer, Polymerisation. Classification of Polymers based on source: Natural polymers, Semi-synthetic polymers, Synthetic polymers. Classification of polymers based on structure: Linear Branched-chain, Cross-linked or Network Polymers. Classification of polymers based on the mode of polymerization: Addition polymers, Condensation polymers.

Classification of Polymers based on Molecular Forces:

Elastomers, Fibres, Thermoplastic And Thermosetting. Types of polymerization. The molecular mass of polymers. Biodegradable polymers. Two Greek words combine to form a term ‘polymer’. In Greek, ‘poly’ means many and ‘mers’ means part or unit. It is also referred to as macromolecules. Examples of polymers are Butadiene, Buna – N etc. Homo-polymers and Copolymers are two types of polymers that are based on their repeating structural unit. A chemical process to produce a chain-like structure or network of molecules called polymer by combining monomers is called polymerization.

There are two types of polymerization reactions:

  • Addition polymerization, it occurs in three steps:

Step 1: Chain initiation
Step 2: Chain propagation
Step 3: Chain termination

  • Condensation polymerization: It is also called step-growth polymerization.

This was the introduction to Chapter 15 of chemistry class 12. Along with NCERT sample questions, one must solve previous year questions and participate in a mock test.

Subtopics of Class 12 Chemistry Chapter 15 – Polymers

  1. Classification of Polymers
  2. Types of Polymerisation Reactions
  3. Molecular Mass of Polymers
  4. Biodegradable Polymers
  5. Polymers of Commercial Importance

Why Opt for SWC’S?

SWC’S gives you polymers Class 12 important questions, polymer pdf book, polymers Class 12 videos, animations, lecture notes on polymers and the assignments that will help you immensely in your Class 12 and entrance exam preparation.

Frequently Asked Questions on NCERT Solutions for Class 12 Chemistry Chapter 15

What are the types of polymerization reactions covered in the Chapter 15 of NCERT Solutions for Class 12 Chemistry?

The types of polymerization reactions covered in the Chapter 15 of NCERT Solutions for Class 12 Chemistry are –
1. Addition polymerization which includes three steps
Chain initiation
Chain propagation
Chain termination
2. Condensation polymerization also known as step growth polymerization.

What are the topics discussed in the Chapter 15 of NCERT Solutions for Class 12 Chemistry?

The topics discussed in the Chapter 15 of NCERT Solutions for Class 12 Chemistry are –
1. Classification of Polymers
2. Types of Polymerisation Reactions
3. Molecular Mass of Polymers
4. Biodegradable Polymers
5. Polymers of Commercial Importance

Why should I opt for SWC’S NCERT Solutions for Class 12 Chemistry Chapter 15?

The subject experts at SWC’S prepare chapter wise and exercise wise solutions to help students with their board exam preparation. Each solution is prepared with utmost care by keeping in mind the grasping abilities of students. A simple and understandable language is used in explaining complex topics to boost confidence among students. PDF format of solutions are available with a free download option which can be accessed by the students without any time constraints.


swc google search e1651044504923
2021 Result Highlight of Swastik Classes

NCERT Solutions Class 12 Chemistry Chapters

  • Chapter 1 The Solid State
  • Chapter 2 Solutions
  • Chapter 3 Electrochemistry
  • Chapter 4 Chemical Kinetics
  • Chapter 5 Surface Chemistry
  • Chapter 6 General Principles and Processes of Isolation of Elements
  • Chapter 7 The p-Block Elements
  • Chapter 8 The d-and f-Block Elements
  • Chapter 9 Coordination Compounds
  • Chapter 10 Haloalkanes and Haloarenes
  • Chapter 11 Alcohols, Phenols and Ethers
  • Chapter 12 Aldehydes, Ketones and Carboxylic Acids
  • Chapter 13 Amines
  • Chapter 14 Biomolecules
  • Chapter 15 Polymers
  • Chapter 16 Chemistry in Everyday Life

SSAT