NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques

NCERT Solutions for Class 11 Chemistry Chapter 12 – Free PDF Download

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry – Some Basic Principles and Techniques is a very crucial resource material for the students in order to score well in their Class 11 examination and entrance examinations like NEET, IIT and state board entrance tests. These NCERT Solutions for Class 11 Chemistry comprehensively help you to get well versed with the chapter by giving answers to the questions given in the textbooks.

The NCERT Solutions for Class 11 Chemistry are prepared by experts at BYJU’S  having vast experience in the subject. Precise explanations are provided for ease of understanding. Students can now access the PDF of NCERT Solutions for Class 11 Chemistry Chapter 11 from the link attached below for free.

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NCERT Solutions for Chemistry – Class 11, Chapter 12 Organic Chemistry – Some Basic Principles and Techniques

Students of Class 11 who are looking to give their best for the upcoming Class 11 final exams and competitive exams, need to be accustomed to NCERT Solutions for Class 11 Chemistry Chapter 12. With the help of these NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry Some Basic Principles and Techniques, we can prepare for the exams effectively.

Subtopics of Class 11 Chemistry Chapter 12 – Organic Chemistry – Some Basic Principles and Techniques

  1. General Introduction
  2. Tetravalence Of Carbon: Shapes Of Organic Compounds
  3. Structural Representations Of Organic Compounds
    1. Complete, Condensed And Bond-line Structural Formulas
    2. Three-dimensional Representation Of Organic Molecules
  4. Classification Of Organic Compounds
  5. Nomenclature Of Organic Compounds
    1. The IUPAC System Of Nomenclature
    2. Iupac Nomenclature Of Alkanes
    3. Nomenclature Of Organic Compounds Having Functional Group(S)
    4. Nomenclature Of Substituted Benzene Compounds  
  6. Isomerism
    1. Structural Isomerism
    2. Stereoisomerism
  7. Fundamental Concepts In Organic Reaction Mechanism
    1. Fission Of A Covalent Bond
    2. Nucleophiles And Electrophiles
    3. Electron Movement In Organic Reactions
    4. Electron Displacement Effects In Covalent Bonds
    5. Inductive Effect
    6. Resonance Structure
    7. Resonance Effect
    8. Electromeric Effect (E Effect)
    9. Hyperconjugation
    10. Types Of Organic Reactions And Mechanisms
  8. Methods Of Purification Of Organic Compounds
    1. Sublimation
    2. Crystallization
    3. Distillation
    4. Differential Extraction
    5. Chromatography
  9. Qualitative Analysis Of Organic Compounds
    1. Detection Of Carbon And Hydrogen
    2. Detection Of Other Elements
  10. Quantitative Analysis
    1. Carbon And Hydrogen
    2. Nitrogen
    3. Halogens
    4. Sulphur
    5. Phosphorus
    6. Oxygen

After reading this concept, students will understand the reasons for the tetravalence of carbon and the shapes of organic molecules.

  • Students will also understand the concept of an organic reaction mechanism
  • Students will be able to name the compounds according to the IUPAC system of nomenclature and also derive their structures from the given names.
  • Learn the techniques of purification of organic compounds
  • Three-Dimensional Representation of Organic Molecules

Class 11 Chemistry NCERT Solutions (Organic Chemistry – Some Basic Principles and Techniques) – Important questions

Exercises

Question 12.1:

What are hybridisation states of each carbon atom in the following compounds?

CH2=C=O, CH3CH=CH2, (CH3)2CO, CH2=CHCN, C6H6

Answer 12.1:

(i)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.1(i)

C–1 is sp2 hybridised.

C–2 is sp hybridised.

(ii)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.1(ii)

C–1 is sp3 hybridised.

C–2 is sp2 hybridised.

C–3 is sp2 hybridised.

 

(iii)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.1(iii)

C–1 and C–3 are sp3 hybridised.

C–2 is sp2 hybridised.

 

(iv)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.1(iv)
C–1 is sp2 hybridised.

C–2 is sp2 hybridised.

C–3 is sp hybridised.

(v) C6H6

All the 6 carbon atoms in benzene are sp2 hybridised.

Question 12.2:

Indicate the σ and π bonds in the following molecules:

C6H6, C6H12, CH2Cl2, CH2 = C = CH2, CH3NO2, HCONHCH3

Answer 12.2:

(i) C6H6

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.2(i)

There are six C – C sigma bonds, six C–H sigma bonds, and three C=C pi resonating bonds in the given compound.

(ii) C6H12

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.2(ii)
There are six C – C sigma bonds and twelve C–H sigma bonds in the given compound.

(iii) CH2Cl2

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.2(iii)
There are two C – Cl sigma bonds and two C–H sigma bonds in the given compound.

(iv) CH2 = C = CH2

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.2(iv)
There are two C–C sigma bonds, four C–H sigma bonds, and two C=C pi bonds in the given compound.

(v) CH3NO2

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.2(v)
There are three C–H sigma bonds, one C–N sigma bond, one N–O sigma bond, and one N=O pi bond in the given compound.

(vi) HCONHCH3

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.2(vi)

There are four C–H sigma bonds, two C–N sigma bond, one N–H sigma bond, and one C=O pi bond in the given compound.

Question 12.3:

Write bond-line formulas for: Isopropyl alcohol, 2, 3–dimethyl butanal, Heptan–4–one.

Answer 12.3:

Isopropyl alcohol

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.3-1
2, 3–dimethyl butanal

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.3-2
Heptan–4–one

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.3-3

Question 12.4:

Give the IUPAC names of the following compounds:

(a)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(a)

 (b)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(b)

 (c)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(c)

 (d)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(d)

 (e)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(e)

(f) Cl2CHCH2OH

Answer 12.4:

(a)

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(a) ans

Propylbenzene

(b)

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(b) ans

3–methylpentanenitrite

(c)

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(c) ans

2, 5–dimethyl heptane

(d)

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(d) ans

3–bromo–3–chloroheptane

(e)

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.4(e) ans

3–chloropropanal

(f) Cl2CHCH2OH

2, 2–dichloroethanol

Question 12.5:

Which of the following represents the correct IUPAC name for the compounds concerned?

(a) 2,2-Dimethylpentane or 2-Dimethylpentane

(b) 2,4,7-Trimethyloctane or 2,5,7-Trimethyloctane

(c) 2-Chloro-4-methylpentane or 4-Chloro-2-methylpentane

(d) But-3-yn-1-ol or But-4-ol-1-yne

Answer 12.5:

(a) The prefix di shows that there are two methyl groups in the chain. Thus, the correct IUPAC name would be 2,2-Dimethylpentane.

(b) The locant number should start from the minimum. Here, 2,4,7 is lower than 2,5,7. Thus, the correct IUPAC name would be 2,4,7-Trimethyloctane.

(c) If the substituents in the chain are in equivalent positions, then the lower number is given to the substituent group in alphabetical order. Thus, the correct IUPAC name would be 2-Chloro-4-methylpentane.

(d) Out of the two functional groups present in the given compound, the alcoholic group is the principal functional group. Thus, the parent chain will have an –ol suffix. Since the alkyne group is in C–3, the IUPAC name would be But–3–yn–1–ol.

Question 12.6:

Draw formulas for the first five members of each homologous series beginning with the following compounds

(a) H–COOH

(b) CH3COCH3

(c) H–CH=CH2

Answer 12.6:

The first five members of each homologous series beginning with the given compounds are

(a)

H–COOH: Methanoic acid

CH3–COOH: Ethanoic acid

CH3–CH2–COOH: Propanoic acid

CH3–CH2–CH2–COOH: Butanoic acid

CH3–CH2–CH2–CH2–COOH: Pentanoic acid

(b)

CH3COCH3: Propanone

CH3COCH2CH3: Butanone

CH3COCH2CH2CH3 : Pentan-2-one

CH3COCH2CH2CH2CH3: Hexan-2-one

CH3COCH2CH2CH2CH2CH3 : Heptan-2-one

(c)

H–CH=CH2: Ethene

CH3–CH=CH2: Propene

CH3–CH2–CH=CH2: 1-Butene

CH3–CH2–CH2–CH=CH2: 1-Pentene

CH3–CH2–CH2–CH2–CH=CH2: 1-Hexene

Question 12.7:

Give condensed and bond line structural formulas and identify the functional group(s) present, if any, for :

(a)2,2,4-Trimethylpentane

(b)2-Hydroxy-1,2,3-propanetricarboxylic acid

(c) Hexanedial

Answer 12.7:

(a) 2, 2, 4–trimethylpentane

Condensed formula

(CH3)2CHCH2C (CH3)3

Bond line formula :

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.7(a)

(b) 2–hydroxy–1, 2, 3–propanetricarboxylic acid

Condensed Formula

(COOH)CH2C(OH) (COOH)CH2(COOH)

Bond line formula:
NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.7(b)

Functional groups:

Carboxylic acid (-COOH) and Hydroxyl (-OH) groups

(c) Hexanedial

Condensed Formula

(CHO)(CH2)4(CHO)

Bond line formula:
NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.7(c)

Functional groups:

Aldehyde (-CHO)

Question 12.8:

Identify the functional groups in the following compounds.

(a) NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.8(a)

(b)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.8(b)

(c)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.8(c)

Answer 12.8:

(a) Hydroxyl (–OH), Aldehyde (–CHO), Methoxy (–OMe),

C=C double bond

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.8(a) ans

(b) Ester -(O = C – O)-, 1oAmino (–NH2) (aromatic), Diethylamine (N(C2H5)2 ) – 3oAmino

(c) Nitro (–NO2),

C=C Ethylenic double bond

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.8(c) ans

Question 12.9:

Which of the two: O2NCH2CH2O or CH3CH2O is expected to be more stable and why?

Answer 12.9:

Since NO2 belongs to the electron-withdrawing group, it shows –I effect. NO2 tries to decrease the negative charge on the compound by withdrawing the electrons toward it. This stabilizes the compound whereas the ethyl group belongs to the electron-releasing group and shows +I effect. This results in an increase in the negative charge on the compound thus destabilizing the compound. Hence, I would expect O2NCH2CH2Oto be more stable than CH3CH2O.

Question 12.10:

Explain why alkyl groups act as electron donors when attached to a π system.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.10

Answer 12.10:

Due to hyperconjugation, an alkyl group behaves as an electron-donor group when attached to a π system. For example, look at propene.

The sigma electrons of the C-H bond get delocalized due to hyperconjugation. The alkyl is attached directly to an unsaturated system. The delocalization happens due to the partial overlap of an sp3-s sigma bond orbital with an empty p orbital of the n bond of an adjacent carbon atom.

This process can be shown as:

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.10 Hyperconjugation

The overlap as shown above results in delocalization making the compounds more stable.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.10 Delocalization

Question 12.11:

Draw the resonance structures for the following compounds. Show the electron shift using curved-arrow notation.

(a) C6H5OH

(b) C6H5NO2

(c) CH3CH = CH – CHO

(d) C6H5CHO

(e) C6H5-CH2

(f)CH3CH=CHCH2

Answer 12.11:

(a) The structure of C6H5OH is: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(a)

Resonating structures: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(a)-1

(b) The structure of C6H5NO2 is: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(b)

Resonating structures: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(b)-1

(c) CH3CH = CH – CHO

Resonating structures: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(c)

(d) The structure of C6H5CHO is: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(d)

Resonating structures: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(d)-1

(e) C6H5-CH

Resonating structures:NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(e)

(f) CH3CH=CHCH2

Resonating structures: NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.11(f)

Question 12.12:

What are electrophiles and nucleophiles? Explain with examples.

Answer 12.12:

A nucleophile is a reagent that has an electron pair and is willing to donate it. It is also known as a nucleus-loving reagent. Ex: NC, OH, R3C (carbanions), etc.

An electrophile is a reagent which is in need of an electron pair and is also known as an electron-loving pair. Ex: Carbonyl groups, CH3CH2+(Carbocations), Neutral molecules (due to the presence of a lone pair).

Question 12.13:

Identify the reagents shown in bold in the following equations as nucleophiles or electrophiles:

(a) CH3COOH + HO\rightarrow CH3COO + H2O

(b) CH3COCH3+ CN \rightarrow (CH3)2C(CN) + (OH)

(c) C6H5 + CH3C+O \rightarrow C6H5COCH3

Answer 12.13:

A nucleophile is a reagent that has an electron pair and is willing to donate it. It is also known as a nucleus-loving reagent.

An electrophile is a reagent which is in need of an electron pair and is also known as an electron-loving pair.

(a) CH3COOH + HO\rightarrow CH3COO + H2O

It is a nucleophile since HO- is electron rich in nature.

(b) CH3COCH3+ CN \rightarrow (CH3)2C(CN) + (OH)

It is a nucleophile since CN is electron rich in nature.

(c) C6H5 + CH3C+O \rightarrow C6H5COCH3

It is an electrophile since CH3C+O is electron-deficient in nature.

Question 12.14:

Classify the following reactions in one of the reaction type studied in this unit.

(a) CH3CH2Br + HS\rightarrowCH3CH2SH + Br

(b) (CH3)2 C=CH2 + HCl\rightarrow(CH3)2ClCCH3

(c) CH3CH2Br + HO\rightarrowCH2=CH2 + H2O + Br

(d) (CH3)3C–CH2 OH + HBr\rightarrow(CH3)2 CBrCH2CH3 + H2O

Answer 12.14:

(a) Substitution (nucleophilic) reaction since bromine group gets substituted by –SH group.

(b) Addition (electrophilic) reaction since two reactant molecules combines to form a single product.

(c) Elimination (bimolecular) reaction since reaction hydrogen and bromine are removed to form ethene.

(d) Substitution (nucleophilic) reaction since rearrangement of atoms takes place.

Question 12.15:

What is the relationship between the members of following pairs of structures? Are they structural or geometrical isomers or resonance contributors?

(a) NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.15(a)

(b) NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.15(b)

(c) NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.15(c)

Answer 12.15:

(a) The given compounds are a pair of structural isomers since they have the same molecular formula but have different structures. These compounds differ in the position of the ketone group. For the first structure, it is in C-3 whereas, for the 2nd one, it is in C-2.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.15(a) ans

(b) The given compounds are a pair of geometrical isomers since they have the same molecular formula, sequence of covalent bonds and the same constitution but differ in the relative positioning of the atoms in space. These compounds differ in the positioning of the Deutrium and Hydrogen.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.15(b) ans

(c) The given compounds are a pair of contributing structures or canonical structures. They do not represent any real molecule and are purely hypothetical. They are also called resonance isomers.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.15(c) ans

Question 12.16:

For the following bond cleavages, use curved-arrows to show the electron flow and classify each as homolysis or heterolysis. Identify reactive intermediate produced as free radical, carbocation and carbanion.

(a)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(a)

(b)NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(b)

(c) NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(c)

(d) NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(d)

Answer 12.16:

(a) The bond cleavage can be shown as:

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(a) ans

It comes under homolytic cleavage since one of the shared pair in a covalent bond goes with the bonded atom. A free radical is formed as the reaction intermediate.

(b) The bond cleavage can be shown as:

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(b) ans
It comes under heterolytic cleavage since the shared remains with the carbon atom of propanone. A carbanion is formed as the reaction intermediate.

(c) The bond cleavage can be shown as:

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(c) ans

It comes under heterolytic cleavage since the shared remains with the bromine ion. A carbocation is formed as the reaction intermediate.

(d) The bond cleavage can be shown as:

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.16(d) ans

It comes under heterolytic cleavage since the shared remains with one of the fragments. A carbocation is formed as the reaction intermediate.

Question 12.17:

Explain the terms Inductive and Electromeric effects. Which electron displacement effect explains the following correct orders of acidity of the carboxylic acids?

(a) Cl3CCOOH > Cl2CHCOOH > ClCH2COOH

(b) CH3CH2COOH > (CH3)2CHCOOH > (CH3)3C.COOH

Answer 12.17:

Electrometric effect

The complete transfer of the shared pair of π electrons to either of the two atoms linked by multiple bonds in the presence of an attacking agent is called the electrometric effect. It can either be – E effect or +E effect.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.17

– E effect: Occurs when electrons are moved away from the attacking agent

+ E effect: Occurs when electrons are moved towards the attacking agent

Inductive effect

Inductive effect involves the permanent displacement of sigma (σ) electrons along a saturated chain, whenever an electron withdrawing or electron donating group is present.

It can either be + I effect or – I effect. When an atom or group attracts electrons towards itself more strongly than hydrogen, it is said to possess – I effect.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.17-1
When the force with which an atom attracts electrons towards itself is greater than that of hydrogen, it is said to exhibit +I effect.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.17-2

(a) Cl3CCOOH > Cl2CHCOOH > ClCH2COOH

The acidity increases with the increase in –I effect which is directly proportional to the number of chlorine atoms.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.17(a)

(b) CH3CH2COOH > (CH3)2 CHCOOH > (CH3)3C.COOH

The acidity increases with the increase in +I effect which is directly proportional to the number of alkyl groups.

NCERT Solutions for Class 11 Chemistry Chapter 12 Organic Chemistry - Some Basic Principles and Techniques Q12.17(b)

Question 12.18:

Give a brief description of the principles of the following techniques taking an example in each case.

(a) Crystallisation

(b) Distillation

(c) Chromatography

Answer 12.18:

(a) Crystallisation

Crystallization is used to purify solid organic compounds.

Principle: The principle on which it works is the difference in the solubility of the compound and impurities in a given solvent. The impure compound is made to dissolve in the solvent at a higher temperature since it is sparingly soluble at lower temperatures. This is continued till we get an almost saturated solution. On cooling and filtering it, we get its’ crystals. Ex: By crystallizing 2-4g of crude aspirin in 20mL of ethyl alcohol, we get pure aspirin. It is heated if needed and left undisturbed until it crystallizes. The crystals are then separated and dried.

(b) Distillation

This method is used to separate non-volatile liquids from volatile impurities. It is also used when the components have a considerable difference in their boiling points.

Principle: The principle on which it works is that liquids having different boiling points vaporise at different temperatures. They are then cooled and the formed liquids are separated.

Ex: A mixture of aniline (b.p = 457 K) and chloroform (b.p = 334 K) is taken in a round bottom flask having a condenser. When they are heated, Chloroform, vaporizes first due to its high volatility and made to pass through a condenser where it cools down. The aniline is left behind in the round bottom flask.

(c) Chromatography

It is widely used for the separation and purification of organic compounds.

Principle: The principle on which it works is that individual components of a mixture move at different paces through the stationary phase under the influence of mobile phase.

Ex: Chromatography can be used to separate a mixture of blue and red ink. This mixture is placed on chromatogram where the component which is less absorbed by the chromatogram moves faster up the paper than the other component which is almost stationary.

Some of the important topics covered in NCERT Solutions for Class 11 Chemistry Chapter 12 are:

  • Tetravalence of carbon
  • Structural representations of organic compounds
  • Classification and nomenclature of organic compounds
  • Isomerism
  • Fundamental concepts in organic reaction mechanisms
  • Methods of purification of organic compounds
  • Qualitative and quantitative analysis

About BYJU’S NCERT Solutions

CBSE or Central Board of Secondary Education is one of the most eminent educational boards of India. Schools affiliated with CBSE are advised to follow the syllabus as well as the textbooks designed by the NCERT. NCERT Solutions are one of the best study materials for students studying in Class 11.

Class 11 Chemistry NCERT book has all the basic and advanced concepts which are needed to score good marks in the examinations. NCERT Solutions for Class 11 Chemistry is designed in such a way that students who want to appear for JEE Mains examination after Class 12 can also go through it. NEET and JEE mains are some of the biggest entrance examinations after Class 12 and to score good marks in these examinations students should solve the NCERT questions.

BYJU’S also provides NCERT Exemplar Problems, MCQs, worksheets and important questions that will help students plan their study and answer appropriately in the examinations.

Frequently Asked Questions on NCERT Solutions for Class 11 Chemistry Chapter 12

What is the main aim of NCERT Solutions for Class 11 Chemistry Chapter 12?

The students are encouraged to go through NCERT Solutions for Class 11 Chemistry Chapter 12 thoroughly before the final exams to score well and intensify their problem-solving abilities. Understanding the concepts and clearing the doubts immediately during self-study is the main aim of these solutions.

What are the key benefits of learning NCERT Solutions for Class 11 Chemistry Chapter 12?

Key benefits of NCERT Solutions for Class 11 Chemistry Chapter 12 are provided here:
1. Students can easily access the solutions for each exercise from the chapters available.
2. The solutions also provide graphs and illustrations that help to understand the concepts clearly.
3. These solutions are prepared by BYJU’S expert team focusing on accuracy.

Why should we refer to NCERT Solutions for Class 11 Chemistry Chapter 12?

Students can refer to these NCERT Solutions for Class 11 Chemistry Chapter 12. They help in gaining knowledge and for better guidance it’s best to solve these solutions. Solving these exercises in this chapter will ensure that students score good marks in the exams.

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