arithmetic progression and geometric progression
TRANSCRIPT
CHEMISTRY (Vol. II)
Written as per the latest textbook prescribed by the Maharashtra State Bureau of Textbook Production and Curriculum Research, Pune.
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Written as per the new textbook Subtopic-wise segregation for powerful concept building Complete coverage of Textual Exercise Questions and Intext Questions ‘Quick Review’ at the end of every chapter facilitates quick revision ‘Reading Between the Lines’ to elucidate concept Video/pdf links provided via QR codes for boosting conceptual retention
Salient Features
Std. XII Sci.
Precise
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tent
This reference book is transformative work based on textbook Chemistry; First edition: 2020 published by the Maharashtra State Bureau of Textbook Production and Curriculum Research, Pune. We the publishers are making this reference book which constitutes as fair use of textual contents which are transformed by adding and elaborating, with a view to simplify the same to enable the students to understand, memorize and reproduce the same in examinations. This work is purely inspired upon the course work as prescribed by the Maharashtra State Bureau of Textbook Production and Curriculum Research, Pune. Every care has been taken in the publication of this reference book by the Authors while creating the contents. The Authors and the Publishers shall not be responsible for any loss or damages caused to any person on account of errors or omissions which might have crept in or disagreement of any third party on the point of view expressed in the reference book. © reserved with the Publisher for all the contents created by our Authors. No copyright is claimed in the textual contents which are presented as part of fair dealing with a view to provide best supplementary study material for the benefit of students.
Disclaimer
Precise Chemistry Std. XII, Vol. II is intended for every Maharashtra State Board aspirant of Std. XII, Science. The scope, sequence, and level of the book are designed to match the new textbook issued by the Maharashtra State board. We understand that Board Examinations can be daunting and the stress of cracking the examination can often leave students struggling to make sense of the curriculum. With the examination in focus, the Precise Series has been specifically designed to make preparation easier, by providing a methodical and organized perspective of the curriculum, thus greatly improving the chances of scoring well. Chemistry is a science that has the potential to unlock the understanding of the natural world by allowing us to appreciate the changes that characterize matter interactions. In order to make sure that students fully grasp the nub of the subject, it is important to present such concepts meaningfully and in an easy to read format. In this vein, the Precise Chemistry book has been crafted to provide an exam-centric approach to the curriculum, while retaining the essence of the subject. Each chapter is thus structured to provide a conceptual foundation, in addition to offering ample practice for acing the board examination. Chemical formulae, bonding structures and chemical equations form the basic building blocks of Chemistry and students are advised to memorise them perfectly. To quote the Nobel prize winner, Marie Curie, “Nothing in life is to be feared. It is only to be understood.” Knowing the simple and basic organic reactions covered in each chapter serves as a foundation for understanding the synthesis of more complex molecules. Students should take advantage of compilation of various organic reactions provided in the book to ascertain their command on solving organic reaction-based problems. A holistic preparation is the key to mastering any subject and conquering the board examination. Our Precise chemistry book adheres to our vision and achieves several goals: building concepts, developing competence to solve numericals, recapitulation and self-study —all while facilitating effective preparation of the chapter. The journey to create a complete book is strewn with triumphs, failures and near misses. If you think we’ve nearly missed something or want to applaud us for our triumphs, we’d love to hear from you. Please write to us on: [email protected] A book affects eternity; one can never tell where its influence stops.
Best of luck to all the aspirants! From, Publisher Edition: First
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FEATURES
Sub topic wise Segregation
Every chapter is segregated sub-topic wise. A subtopic encompasses textual content in the format of Question-Answers. All Textual Exercise questions and Intext questions are placed aptly amongst various additional questions in accordance with the flow of subtopic. This is our attempt to enable easy assimilation of concept and lay strong foundation for understanding as well as writing answers in exam.
Q.6. What are the different ways of classification of polymers?
Ans: Polymers are classified in a number of ways as mentioned below:
i. Classification based on source ii. Classification based on chemical structure of
polymers iii. Classification based on mode of polymerization iv. Classification based on molecular forces v. Classification based on type of monomers vi. Classification based on biodegradability
15.2 Classification of polymers
Reading between the lines
Reading between the lines provides elaboration or missing fragments of concept which is essential for complete understanding of the concept. This is our attempt to help students to understand the underlying concept behind an answer.
Substituted aniline containing electron releasing groups (ERG) such as CH3, –OCH3, NH2 is more basic than aniline. The ERG stabilises the cation, thereby increasing basicity. Substituted aniline containing electron withdrawing groups (EWG) such as –NO2, C6H5, SO3, COOH,
CN, X is less basic than aniline. The EWG destabilises the cation, thereby decreasing basicity. Thus, 4-nitroaniline will have higher pKb value than aniline.
Reading between the lines
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Quick review includes tables/ flow chart to summarize the key points in chapter. This is our attempt to help students to reinforce key concepts.
Quick Review
Quick Review
Classification of amines:
Classification of amines
Aromatic aminesAliphatic amines
QR code provides access to a video/pdf in order to boost understanding of a concept or activity. This is our attempt to facilitate learning with visual aids.
QR Code
[Note: Students can scan the adjacent QR code to view three-dimensional models of 2-chlorobutane and its mirror image.]
FEATURES
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Exercise includes subtopic-wise additional questions and problems. This is our attempt to provide additional practice to students to gauge their preparation.
Exercise
Exercise
12.1 Introduction 1. Carboxylic acids are distinct from aldehydes
and ketones. Why? Ans: Refer Q.2. (iii) 12.2 Classification of aldehydes, ketones and
carboxylic acids 2. Give two examples of following: i. Aliphatic aldehydes ii. Aromatic aldehydes Ans: Refer Q.3.
*22. The best method for preparation of alkyl fluorides is _______.
(A) Finkelstein reaction (B) Swartz reaction (C) Free radical fluorination (D) Sandmeyer's reaction
Multiple Choice Questions Multiple Choice Questions
Multiple Choice Question includes textual as well as additional MCQs. This is our attempt to give students practice of MCQs and prepare them thoroughly for board examination.
FEATURES
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Chapter No. Chapter Name Page No.
10 Halogen Derivatives 1
11 Alcohols, Phenols and Ethers 43
12 Aldehydes, Ketones and Carboxylic Acids 80
13 Amines 127
14 Biomolecules 162
15 Introduction to Polymer Chemistry 197
16 Green Chemistry and Nanochemistry 223
Functional Groups of Organic Compounds 237
[Reference:Maharashtra State Board of Secondary and Higher Secondary Education, Pune 04]
Note: 1. * mark represents Textual question.
2. # mark represents Intext question.
3. + mark represents Textual examples.
4. symbol represents textual questions that need external reference for an
answer.
CONTENTS
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Std. XI Sci.: Perfect Chemistry - I
Q.1. Can you recall? (Textbook page no. 322) i. Classify the following materials as biodegradable and non-biodegradable: Thermocol, glass, wood, cotton clothes, paper bags, polythene bags, nylon ropes, fruit peels. Ans:
Material Biodegradable/ Non-biodegradable Thermocol Non-biodegradable
Glass Non-biodegradable Wood Biodegradable
Cotton clothes Biodegradable Paper bags Biodegradable
Polythene bags Non-biodegradable Nylon ropes Non-biodegradable Fruit peels Biodegradable
ii. Give examples of man-made materials we use in our daily life. Ans: Cement, glass, plastics, dyes, nylon, etc., are some of the man-made materials we use in our daily life. iii. Which material is used in manufacture of toys, combs? Ans: Toys and combs are made of plastic. iv. Write examples of thermosetting plastic articles. Ans: Electrical switches, ropes, pipes, etc., are examples of thermosetting plastic articles. v. List various properties of plastic. Ans: Properties of plastic: a. It is thermal resistant. b. It is resistant to chemical and environmental stress. c. It has high strength and durability. d. Some types of plastics can be melted and remoulded. Q.2. Why has polymer chemistry emerged as a separate branch of chemistry? Ans: Polymer chemistry emerged as a separate branch of chemistry during the last several decades. This is due to the
voluminous knowledge built up in this field and the ever-increasing applications of polymers in our everyday life. Q.3. What are polymers? (NCERT) Ans: i. Chemically polymers are complex, giant macromolecules made from the repeating units which are derived
from small molecules called 'monomers'. ii. Thus, interlinking of many monomers constitute polymers. iii. Polymer have high molecular mass ranging from 103 - 107 u. iv. Both inorganic as well as organic polymers are known. Note: In Greek, ‘poly’ means ‘many’ and ‘mer’ means ‘part’ or ‘unit’.
15.1 Introduction 15.2 Classification of polymers 15.3 Some important polymers
15.4 Molecular mass and degree of polymerization of polymers
15.5 Biodegradable polymers 15.6 Commercially important polymers
Contents and Concepts
15.1 Introduction
Introduction to Polymer Chemistry 15
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*Q.4. Define the term: Monomer Ans: Small molecules that are interlinked together to form polymers are called as monomers. Q.5. Give some examples of organic biopolymers. Ans: Carbohydrates, proteins and nucleic acids. Q.6. What are the different ways of classification of polymers? Ans: Polymers are classified in a number of ways as mentioned below: i. Classification based on source ii. Classification based on chemical structure of polymers iii. Classification based on mode of polymerization iv. Classification based on molecular forces v. Classification based on type of monomers vi. Classification based on biodegradability Q.7. How are polymers classified on the basis of the source or origin? Give two examples of each. Ans: On the basis of the source or origin, polymers are classified into three categories: i. Natural polymers: The polymers obtained from natural source are said to be natural polymers. e.g. cotton and linen. Natural polymers are further subdivided into two types: Plant polymer and animal polymers. ii. Synthetic polymers: These polymers are artificially prepared by polymerization of one monomer or
copolymerization of two or more monomers. e.g. nylon and terylene. Synthetic polymers are further divided into three subtypes: fibres, synthetic rubbers and plastics. iii. Semisynthetic polymers: Polymers which are derived from natural polymers are called semisynthetic
polymers. These are also called regenerated fibres. e.g. cellulose acetate rayon and cellulose nitrate. Q.8. How are natural polymers classified? Ans: Natural polymers are subdivided into two types: i. Plant polymers: These are obtained from plants. For example, cotton and linen are obtained from cotton plant
and flax plant respectively. Natural rubber is manufactured from the latex obtained from bark of rubber trees. ii. Animal polymers: These are derived from animal sources. For example, wool is obtained from hair of
sheep and silk is obtained from silkworm. *Q.9. What are synthetic resins? Name some natural and synthetic resins.
Ans: i. Synthetic resins: Refer Q.7. (ii) ii. a. Natural resins: Natural rubber, silk, wool, etc.
b. Synthetic resins: Nylon, terylene, neoprene, etc. [Note: In polymer chemistry, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers. However, the term ‘resin’ is often used instead of ‘polymer’.] Q.10. How are synthetic polymers classified? Ans: Synthetic polymers are divided into three subtypes i.e., fibres, synthetic rubbers and plastics. Q.11. Mention some uses of semisynthetic polymers. Ans: Uses of semisynthetic polymers are: i. They are used in preparation of non-inflammable photographic films. ii. They are used to make cinema films. iii. They are used in manufacture of varnishes. Q.12. Use your brain power. (Textbook page no. 323) Differentiate between natural and synthetic polymers. Ans: No. Natural polymers Synthetic polymers i. Polymers which are obtained from natural
sources are called natural polymers. Polymers which are man-made or artificially synthesised by polymerization of one monomer or copolymerization of two or more polymers are called synthetic polymers.
ii. These occur naturally. These do not occur naturally.
15.2 Classification of polymers
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iii. Animal and plant polymers are two types of natural polymers.
Fibres, synthetic rubbers and plastics are three types of synthetic polymers.
iv. Most of the natural polymers are easily degraded naturally by biological processes.
Most of the synthetic polymers are not degraded naturally by biological processes.
e.g. Cotton, linen, silk, etc. Nylon, terylene, neoprene, etc. Q.13. Classify the following polymers as natural, synthetic and semisynthetic polymers. Acetate rayon, cotton, nylon, cuprammonium rayon, linen, neoprene, viscose rayon, silk. Ans:
Sr. No. Polymer Type of polymer i. Acetate rayon Semisynthetic ii. Cotton Natural iii. Nylon Synthetic iv. Cuprammonium rayon Semisynthetic v. Linen Natural vi Neoprene Synthetic
vii. Viscose rayon Semisynthetic viii. Silk Natural
*Q.14. Classify the following polymers as natural and synthetic polymers: i. Cellulose ii. Polystyrene iii. Terylene iv. Starch v. Protein vi. Silicones vii. Orlon (Polyacrylonitrile) viii. Phenol-formaldehyde resins Ans:
Sr. No. Polymer Type of polymer i. Cellulose Natural ii. Polystyrene Synthetic iii. Terylene Synthetic iv. Starch Natural v. Protein Natural vi. Silicones Synthetic vii. Orlon (polyacrylonitrile) Synthetic viii. Phenol-formaldehyde resins Synthetic
Q.15. How are polymers classified on the basis of structure? Give few examples of each. Ans: Depending upon how the monomers are linked together, that is, the chain configuration, polymers are
classified in three types: i. Linear or straight chain polymers: When the monomer molecules are joined together in a linear arrangement
the resulting polymer is straight chain polymer. It is obtained from bifunctional monomers or alkenes. e.g. PVC, high density polythene. ii. Branched chain polymers: Monomers having 3 functional groups or already having side chains give rise to
branched chain polymers. e.g. Low density polythene. iii. Three dimensional cross-linked polymers: Third type of arrangement is said to be cross linked or network
polymers where cross links are produced between linear chains. Cross linking results from polyfunctional monomers.
e.g. Bakelite, melamine. Note:
i. ii. iii.
Different chain configurations of polymers
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*Q.16. Classify the following polymers as straight chain, branched chain and cross-linked polymers. i. ii. iii. Ans: i. Straight chain polymer ii. Branched chain polymer iii. Crosslinked polymer Q.17. What is polymerization? Ans: Polymerization is the fundamental process by which low molecular mass compounds are converted into high
molecular weight compounds by linking together of repeating structural units with covalent bonds. Low molecular mass material High temperature
and/or Pr essureand/or catalyst
High molecular mass material
(Possessing reactive groups) Q.18. Name the modes of polymerization according to the types of reactions taking place between the
monomers. Ans: The three modes of polymerization according to the types of reactions taking place between the monomers
are: Addition polymerization, Condensation polymerization and Ring opening polymerization. *Q.19. Draw the flow chart diagram to show classification of polymers based on type of polymerization. Ans: Q.20. Explain addition polymerization. Ans: Addition polymerization (or chain growth polymerization): i. Addition polymerization is a process of formation of polymers by addition of monomers without loss of any
small molecules. ii. The repeating unit of an addition polymer has the same elemental composition as that of original monomer. iii. Compounds containing double bond undergo addition polymerization. It is also referred as vinyl
polymerization, since majority of monomers are from vinyl category such as: vinyl chloride (CH2 = CHCl), acrylonitrile (CH2 = CHCN) iv. Addition polymerization produces high molecular mass polymeric materials without formation of any
intermediate low molecular mass polymeric materials. v. Formation of polyethylene (polythene) from ethene is an example of addition polymerization.
– (CH2 – CH –)n
CN
–(CH2 – CH2 – CH – CH2 – CH2 –)n
CH2
CH2 OH H2C CH2
CH2
OH CH2
OH CH2
H2C OH
CH2
(Bakelite)
OH CH2
CH2
OH CH2
CH2 CH2
Polymers
Classification based on type of polymerization
Addition polymers e.g. Polythene
Condensation polymers e.g. Terylene
Ring opening polymerse.g. Nylon-6
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*Q.21. Name some chain growth polymers. Ans: Chain growth polymers: polyacrylonitrile, polyvinylchloride, polythene, etc.
*Q.22. Explain in detail free radical mechanism involved during preparation of addition polymer. Ans: Free radical mechanism is most common in addition polymerization. It is also called chain reaction which
involves three distinct steps. These are as follows: i. Step 1: Chain initiation: a. The chain reaction is initiated by a free radical which is formed from an initiator (catalyst) such as
benzoyl peroxide, acetyl peroxide, tert-butyl peroxide, etc. b. For example, acetyl peroxide generates methyl radical as shown below:
c. The free radical (say R ) so formed attaches itself to the olefin (vinyl monomer) and produces a new radical, made up of two parts, namely, the attached radical and the monomer unit.
ii. Step 2: Chain propagation: a. The new radical formed in the initiation step reacts with another molecule of vinyl monomer, forming
another still bigger sized radical, which in turn reacts with another monomer molecule. b. The repetition of this sequence takes place very rapidly. It is called chain propagation. c. This step is very rapid and leads to high molecular mass radical.
iii. Step 3: Chain termination:
a. At some stage, termination of the growing chain takes place. It may occur by several processes. b. One mode of termination is by combination of two growing chain radicals. Q.23. Explain condensation polymerization. Ans: Condensation polymerization (or step growth polymerization): i. The process of formation of polymers from polyfunctional monomers with the elimination of some small
molecules such as water, hydrochloric acid, methanol, ammonia is called condensation polymerization. ii. In this type of polymerization, the chain growth occurs by a series of condensation steps until a high
molecular mass polymer is obtained. Therefore, it is also referred to as step growth polymerization. iii. Repeating units of condensation polymer do not have the same elemental composition as that of monomer. iv. Formation of terylene, a polyester polymer, from ethylene glycol and terephthalic acid is an example of
condensation polymerization.
In this reaction, an alcoholic OH group in ethylene glycol condenses with a carboxyl group in terephthalic acid by eliminating a water molecule to form an ester linkage.
Q.24. Explain ring opening polymerization. Ans: Ring opening polymerization: i. The polymerization that proceeds by addition of a single monomer unit (but never of larger units) to the
growing chain molecules is called ring opening polymerization. ii. Since the polymer chain grows step-wise, the ring opening polymerization is similar to condensation
polymerization.
CH3 C O O C CH3 2CH3 C O 3CO2CH
Acetyl peroxide Methyl radical
O O O
R + CH2 = CHY R CH2 – CHY Free
radical Vinyl
monomerNew radical
R CH2 CHY + nCH2 = CHY R ( CH2 – CHY )n CH2 – CHY
2R ( CH2 CHY )n CH2 – CHY R ( CH2CHY)n + 1 (CHYCH2)n + 1 R (Polymer)
Ethylene glycol Terephthalic acid
Terylene or dacron Ester link
n
n HO CH2 CH2 – OH + n HOOC – – COOH nH O2 H –– OCH2 – CH2 – O – C –– C OH
O O
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Std. XII Sci.: Precise Chemistry (Vol. II) iii. Elemental composition of the repeating unit in the polymer resulting from ring opening polymerization is
same as that of the monomers. iv. Cyclic compounds like lactams, cyclic ethers, lactones, etc. polymerize by ring opening polymerization,
catalysed by strong acid or a base. e.g. Polymerization of ɛ-caprolactam:
Q.25. Use your brain power (Textbook page no. 325) What is the type of polymerization in the following examples? i. ii. Ans: i. Addition or chain growth polymerization. ii. Condensation or step growth polymerization.
*Q.26. Write the names of classes of polymers formed according to intermolecular forces and describe briefly their structural characteristics.
Ans: i. Polymers are classified into various categories on the basis of intermolecular forces as follows: a. Elastomers b. Fibres c. Thermoplastic polymers d. Thermosetting polymers ii. Their structural characteristics are as follows: a. Elastomers: 1. Elastomers have the property of elasticity in which a substance gets stretched by external force and
restores its original shape on release of that force. 2. Elastomers, the elastic polymers, have weak van der Waals type of intermolecular forces which permit
the polymer to be stretched. 3. A few crosslinks between the chains help the stretched polymer to retract to its original position on
removal of applied force. e.g. Vulcanized rubber, Buna-S, Buna-N, neoprene, etc. b. Fibres: 1. Polymeric solids which form threads are called fibres. 2. The fibres possess high tensile strength which is a property to have resistance to breaking under tension. 3. High tensile strength is due to the strong intermolecular forces like hydrogen bonding and strong
dipole-dipole forces. Due to these strong intermolecular forces the fibres are crystalline in nature. e.g. Polyamides (nylon 6,6), polyesters (terylene), etc. c. Thermoplastic polymers: 1. Thermoplastic polymers have the property of plasticity, that is, these polymers can be easily shaped or moulded. 2. They are capable of repeated softening on heating and hardening on cooling. 3. These polymers possess moderately strong intermolecular forces that are intermediate between
elastomers and fibres. e.g. Polythene, polystyrene, polyvinyls, etc. d. Thermosetting polymers: 1. Thermosetting polymers are rigid polymers. 2. During their formation, they have property of being shaped on heating; but they get hardened while
hot. Once hardened, they cannot be softened by heating and therefore cannot be remoulded. 3. This characteristic is the result of extensive cross linking by covalent bonds formed in the moulds
during hardening/setting process while hot. e.g. Bakelite, urea formaldehyde resin, etc.
NH H2C C
H2C CH2
CH2 – CH2
O
n H O2533 543 K [ NH ( CH2)5 CO ]n
Nylon 6
ɛ-Caprolactam
2n CH2 = CH – CH3CH3 H3C ( CH2 – CH) (CH – CH2 ) CH3
CH3 CH3
n n
nHO – (CH2)x – OH + nHOOC – (CH2)y– COOH H [ O – (CH2)x – O – CO – (CH2)y– CO ] OH n
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*Q.27. Distinguish between thermosetting and thermoplastic resins. Write example of both the classes. Ans:
Thermosetting resin Thermoplastic resin i. They do not soften on heating. They soften on heating and harden on cooling. ii. They cannot be remoulded or reshaped. These can be remoulded or reshaped. iii. They possess extensive cross linking
formed by covalent bonds. They possess moderately strong intermolecular forces that are intermediate between elastomers and fibres.
iv. They are rigid polymers. They are not rigid polymers. e.g. Bakelite, urea-formaldehyde resins, etc. PVC, polythene, polystyrene, etc.
*Q.28. Define the term: Synthetic fibres Ans: Man-made polymeric solids which form threads are called synthetic fibres. Q.29. State whether True or False. If false, rewrite the correct statement. i. The nature of linking the monomers depends upon the nature and number of functional groups in them. ii. Repeating units of condensation polymer have the same elemental composition as that of monomer. Ans: i. True ii. False
Repeating units of condensation polymer do not have the same elemental composition as that of monomer. Q.30. Give the classification of polymers on the basis of types of different monomers. Ans: On the basis of type of different monomers present, polymers are classified as homopolymers and copolymers. Q.31. Explain the terms: i. Homopolymers ii. Copolymers Ans: i. Homopolymers: a. The polymers which have only one type of repeating unit are called homopolymers.
b. They are formed from a single monomer. In certain cases, the repeating unit is formed by condensation of two distinct monomers.
e.g. Polythene, polypropene, Nylon 6, polyacrylonitrile, Nylon 6,6. ii. Copolymers:
a. The polymers which have two or more types of repeating units are called copolymers. b. They are formed by polymerization of two or more different types of monomers in presence of each other. c. The different monomer units are randomly sequenced in the copolymer. e.g. Buna-S, Buna-N.
+Q.32. Refer to the following table listing for different polymers formed from respective monomer. Identify from the list whether it is copolymer or homopolymer.
Sr. No. Monomer Polymers i. Ethylene Polyethylene ii. Vinyl chloride Polyvinyl chloride iii. Isobutylene Polyisobutylene iv. Acrylonitrile Polyacrylonitrile v. Caprolactum Nylon 6 vi. Hexamethylenediammoniumadipate Nylon-6,6 vii. Butadiene + styrene Buna-S
Ans: In each of first five cases, there is only one monomer which gives corresponding homopolymer. In the sixth case, hexamethylenediamine reacts with adipic acid to form the salt hexamethylenediammonium
adipate which undergoes condensation to form Nylon 6, 6. Hence, nylon-6,6 is homopolymer. The polymer Buna-S is formed by polymerization of the monomers: butadiene and styrene in presence of
each other. The repeating units corresponding to the monomers butadiene and styrene are randomly arranged in the polymer. Hence, Buna-S in copolymer.
*Q.33. Give one example each of homopolymer and copolymer. Ans: i. Homopolymer: Polythene. ii. Copolymer: Buna-S.
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Q.34. How are polymers classified on the basis of biodegradability? Ans: On the basis of biodegradability, polymers are classified as: i. Non-biodegradable polymers: These synthetic polymers are not affected by microbes. Hence, they stay in
environment for very long time and pose pollution hazards. ii. Biodegradable polymers: These synthetic polymers can be degraded by microbes. Q.35. Polymers are classified in a number of ways. Sketch a tree diagram showing the classification of polymers. Ans:
Q.36. Write a note on natural rubber. Ans: Natural rubber: i. Natural rubber is polymer made of monomer isoprene (2-methyl-1,3-butadiene). ii. Natural rubber is a high molecular mass linear polymer of isoprene. Its molecular mass varies from
130,000 u to 340,000 u (that is, the number of monomer units varies from 2000 to 5000). iii. Reaction involved in formation of natural rubber from isoprene by the process of addition polymerization is
as follows:
*Q.37. Name and draw structure of the repeating unit in natural rubber. Ans: Repeating unit in natural rubber is obtained from the monomer isoprene. Structure of repeating unit is:
15.3 Some important polymers
CH2 = C CH = CH2
CH3
Isoprene
Natural rubber
C = C H
CH2 H2C
H3C
C = C CH2
H H3C
CH2 C = C H
CH2 CH2
H3C
–– C C = C C ––
H CH3 H H
H H
Polymers
Based on source or origin Based on structure Based on inter-
molecular forces Based on mode of
polymerization No. of monomers
Synthetic
Natural
Semisynthetic
Branched chain
Linear
Cross-linked
Fibers
Elastomers
Thermoplastic
Thermosetting
Condensation
Addition
Ring opening
Copolymers
Homopolymers
Biodegradability
Non-biodegradable
Biodegradable
nH2C = C–––C = CH2Polymerization –– C C = C C ––
CH3 H H CH3 H H
HH
n Polyisoprene/rubber Isoprene Sam
ple C
onten
t
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Std. XII Sci.: Precise Chemistry (Vol. II)
Classification of polymers:
Quick Review
Based on source or origin
Based on structure
Based on intermolecularforces
Based on mode of polymerization
Based on type of different monomers
Based on biodegradability
Natural polymers e.g. Cotton, Silk
Synthetic polymers e.g. Terylene, Nylon
Semisynthetic polymers e.g. Viscose rayon
Linear polymers e.g. PVC, HDP
Branched chain polymers e.g. LDP
Cross-linked polymers e.g. Bakelite
Elastomers e.g. Neoprene
Fibres e.g. Nylon 6,6
Thermoplastic polymers e.g. Polythene
Thermosetting polymers e.g. Bakelite
Addition e.g. Polythene
Condensation e.g. Bakelite
Ring opening e.g. Nylon 6
Homopolymers e.g. Pdythene
Copolymers e.g. Buna-S
Non-biodegradable polymers e.g. PVC
Biodegradable polymers e.g. PHBV
Polymers
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Some important polymers: Rubbers:
Polythene:
Polyamides:
Polyesters:
Polythene CH2 – CH2 n
LDP
HDP
Branched polymer
Linear polymer
Polyamides (Nylon)
Nylon 6,6
Nylon 6
Monomers: Adipic acid and Hemamethylenediamine Structure of polymer:
Monomer: -Caprolactum Structure of polymer:
C ( CH2)4 – C – NH – (CH2)6 – N n
O O H
NH ( CH2)5 – CO n
Polyesters Terylene (Dacron)
Monomers: Ethylene glycol and Terephthalic acid Structure of polymer:
O – CH2 – CH2 – O – C n
O
C
O
Buna-N
Monomers: Styrene and butadiene Structure of polymer: C6H5
CH2– CH = CH – CH2– CH2– CH = CH – CH2– CH2– CH – CH2– CH2– CH = CH
CN
[ H2C – CH=CH – CH2– CH2 – CH ] n
Monomer: Acrylonitrile and butadiene Structure of polymer:
Monomer: Chloroprene Structure of polymer:
CH2 – C = CH – CH2
Cl
n
Buna-S
Neoprene
Monomer: Isoprene Structure of polymer:
Natural rubber CH2 – C = CH – CH2
CH3
n
Synthetic rubbers
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Other common polymers:
Biodegradable polymers:
Biodegradable polymers PHBV Nylon 2-nylon 6
Monomers: -Hydroxybutyric acid (3-hydroxybutanoic acid) and -hydroxyvaleric acid (3-hydroxypentanoic acid).
Structure of polymer:
Monomers: Glycine and -amino caproic acid Structure of polymer:
15.1 Introduction 1. Define polymers. Ans: Refer Q.3. (i) 2. Define monomers. Ans: Refer Q.4.
15.2 Classification of polymers 3. Mention the different ways of classification of
polymers. Ans: Refer Q.6. 4. Explain the classification of natural polymers.
Give examples. Ans: Refer Q.8.
Exercise
[ O CH CH2 C O CH CH2 C ]n
CH3 O CH2 CH3
O
[ C CH2 NH C ( CH2)5 NH ]n
O O
Teflon
CF2 – CF2 n
Monomer: Tetrafluoroethylene Structure of polymer:
Polyacrylonitrile Monomer: Acrylonitrile Structure of polymer:
N
N –CH2N N
N N H2C
[ H2C H
H H
n
Melamine-formaldehyde polymer (Melamine) Monomers: Melamine and formaldehyde Structure of polymer:
CH2 – CH n
CN
OH H2C CH2
CH2
OH CH2
OH CH2
H2C OH
CH2 OH
CH2
CH2
OH CH2
CH2 CH2
Phenol-formaldehyde polymer (Bakelite) Monomers: Phenol and formaldehyde Structure of polymer:
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Chapter 15: Introduction to Polymer Chemistry5. Give any two uses of semisynthetic polymers. Ans: Refer Q.11. 6. Give two examples of network polymers. Ans: Refer Q.15. (iii) 7. Define polymerization. Ans: Refer Q.17. (Definition) 8. Draw the flow chart diagram to show
classification of polymers based on type of polymerization.
Ans: Refer Q.19. 9. Define addition polymerization. Ans: Refer Q.20. (i) 10. Describe in detail free radical mechanism
involved during the preparation of an addition polymer.
Ans: Refer Q.22. 11. Define condensation polymerization. Ans: Refer Q.23. (i) 12. Write a note on thermoplastic polymers. Ans: Refer Q.26. (ii-c) 13. Differentiate between thermosetting and
thermoplastic resins. Ans: Refer Q.27. 14. Define homopolymers. Ans: Refer Q.31. (i-a) 15. Define copolymers. Ans: Refer Q.31. (ii-a) 15.3 Some important polymers 16. Draw the structure of isoprene and the polymer
obtained from it. Ans: Refer Q.38. 17. Give two uses of LDP. Ans: Refer Q.45. (ii) 18. Explain preparation of HDP. Ans: Refer Q.46. 19. Explain the preparation of teflon. Ans: Refer Q.51. 20. Write the chemical reaction involved in
preparation of polyacrylonitrile. Ans: Refer Q.54. (i) 21. Write the chemical reactions involved in
preparation of Nylon 6,6. Ans: Refer Q.56. (ii) 22. Give the chemical reaction involved in
manufacture of Nylon 6. Ans: Refer Q.59. (i)
23. Draw polymer structure of terylene. Ans: Refer Q.61. (only polymer structure) 24. Write the uses of: i. Nylon 6 ii. Bakelite. Ans: i. Refer Q.59. (ii) ii. Refer Q.71. (ii) 25. Write the chemical reaction involved in
manufacture of melamine-formaldehyde polymer.
Ans: Refer Q.75. (i) 15.4 Molecular mass and degree of polymerization
of polymers 26. Define degree of polymerization. Ans: Refer Q.86. 27. Explain why critical degree of polymerization is
low for nylon 6 while high for polythene. Ans: Refer Q.89. 15.5 Biodegradable polymers 28. Write the chemical reaction involved in
preparation of nylon 2-nylon 6. Ans: Refer Q.94. (i) 29. Give the name and structure of monomers of
nylon 2-nylon 6. Ans: Refer Q.94. (i) 30. Write the chemical reaction involved in
preparation of PHBV. Ans: Refer Q.95. (iv) 15.6 Commercially important polymers 31. Draw polymer structure of Buna-N and Glyptal. Ans: Refer Q.98. (Table) 32. Give the name and structure of monomer of
Thermocol and Perspex. Ans: Refer Q.98. (Table) 33. Name the monomers of Glyptal and
polycarbonate. Ans: Refer Q.98. (Table)
*1. Chemically pure cotton is _______. (A) acetate rayon (B) viscose rayon (C) cellulose nitrate (D) cellulose
*2. Silk is a kind of _______ fibre. (A) semisynthetic (B) synthetic (C) animal (D) vegetable
*3. Which of the following is naturally occurring polymer?
(A) Teflon (B) Polyethylene (C) PVC (D) Protein
Multiple Choice Questions
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Std. XII Sci.: Precise Chemistry (Vol. II) 4. Which of the following is an example of
semisynthetic polymer? (A) Acetate rayon (B) Neoprene (C) Linen (D) Nylon 5. _______ is a network polymer. (A) LDP (B) Melamine (C) HDP (D) PVC 6. Which of the following is NOT an example of
elastomers? (A) Vulcanised rubber (B) Buna-S (C) Nylon 6,6 (D) Neoprene 7. Which of the following can be reshaped again
and again? (A) Thermosetting polymers (B) Fibres (C) Thermoplastic polymers (D) Elastomers 8. The monomer of natural rubber: (A) Chloroprene (B) Isoprene (C) Ethene (D) Styrene 9. The Zieglar-Natta catalyst is used in the
preparation of _______. (A) LDPE (B) PHBV (C) PAN (D) HDPE
*10. Teflon is chemically inert, due to presence of _______.
(A) C-H bond (B) C-F bond (C) H- bond (D) C=C bond
*11. Nylon fibres are _______. (A) semisynthetic fibres (B) polyamide fibres (C) polyester fibres (D) cellulose fibres 12. When nylon salt polymerises to Nylon-6,6,
temperature required is ______. (A) 553 K (B) 273 K (C) 373 K (D) 800 K
*13. The number of carbon atoms present in the ring of ɛ-caprolactam is _______.
(A) five (B) two (C) seven (D) six
*14. Which of the following is made up of polyamides?
(A) Dacron (B) Rayon (C) Nylon (D) Jute
*15. Terylene is _______. (A) polyamide fibre (B) polyester fibre (C) vegetable fibre (D) protein fibre
16. A polymer which contains ester linkage is_______.
(A) teflon (B) buna-N (C) terylene (D) neoprene
*17. Dacron is another name of _______. (A) nylon 6 (B) orlon (C) novolac (D) terylene
*18. PET is formed by _______. (A) addition (B) condensation (C) alkylation (D) hydration 19. Bakelite is the polymer of _______. (A) benzaldehyde and phenol (B) acetaldehyde and phenol (C) formaldehyde and phenol (D) formaldehyde and benzyl alcohol 20. Buna-S is an elastomer which is a copolymer of
________ with butadiene. (A) styrene (B) acrylonitrile (C) phenol (D) chloroprene 21. Cellulose in the form of wood pulp is
transformed into _______. (A) polyacrylonitrile (B) terylene (C) nylon (D) viscose rayon 22. Which of the following is a biodegradable
polymer? (A) Teflon (B) Nylon 2–nylon 6 (C) LDP (D) Nylon 6,6 23. Nylon-2-nylon-6 is obtained by the
condensation polymerization of the monomers _______.
(A) glycine and lactic acid (B) alanine and -aminocaproic acid (C) glycine and -aminocaproic acid (D) alanine and lactic acid 24. Which of the following is used in paints and
lacquers? (A) Polyacrylamide (B) Glyptal (C) LDP (D) Thermocol 1. (D) 2. (C) 3. (D) 4. (A) 5. (B) 6. (C) 7. (C) 8. (B) 9. (D) 10. (B) 11. (B) 12. (A) 13. (D) 14. (C) 15. (B) 16. (C) 17. (D) 18. (B) 19. (C) 20. (A) 21. (D) 22. (B) 23. (C) 24. (B)
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