NCERT Solutions for Class 12 Chemistry Chapter 10 – Haloalkanes and Haloarenes
NCERT Solutions for Class 12 Chemistry Chapter 10 – Haloalkanes and Haloarenes offer comprehensive coverage of this Chapter of Organic Chemistry. This chapter teaches you about haloalkanes and haloarenes, their structure and nomenclature, chemical reactions involved in their preparation and reactions shown by them with other reagents. This chapter further imparts knowledge about correlating the structures of haloalkanes and haloarenes to various reactions, using stereochemistry as a tool to understand the mechanisms of reactions shown by them. This chapter also deals with organometallic compounds and effects of polyhalogen compounds on the environment.
There are 22 questions at the end of the chapter. All of these questions have been answered, following all the guidelines given by CBSE and NCERT Solutions. These are designed to cover all the concepts taught in NCERT CBSE Class 12 Chemistry Chapter 10. The questions asked in this chapter are about the IUPAC nomenclature of halogen-containing organic compounds, converting structures to names and vice versa, reaction mechanisms, predicting products and reaction conditions, structures and names of isomers and applications of polyhalogen compounds.
All of these questions have been answered precisely in Class 12 Chemistry Chapter 10 – Haloalkanes and Haloarenes. The solutions are framed in such a way that they make the learning process engaging, interactive and efficient.
NCERT Class 12 Chemistry Chapter 10: Important Topics
NCERT Solutions for Class 12 Chemistry Chapter 10 – Haloalkanes and Haloarenes include all the concepts of this chapter. They give you a complete understanding of the topics and subtopics covered in this chapter. The main points given in this chapter are as follows.
This part of the chapter talks about classifying the carbon compounds containing halogens on the basis of the number of halogens atoms attached to the carbon atom as mono-, di-, or polyhalogen compounds.
- Compounds containing Carbon – Halogen bond
This part of the chapter tells you that compounds containing an sp3 carbon attached to halogen are alkyl halides, allylic halides, benzylic halides and those which contain sp2 C – X bond are vinyl halides and aryl halides.
This part of the chapter makes you aware of the definite rules for giving IUPAC names to the halogen-containing carbon compounds.
- Nature of C-X Bond
This part of the chapter discusses that C-X bond is polarised because there is an electronegativity difference between halogen atom and carbon atom, halogen being more electronegative bears a partial negative charge and the carbon atom carries a partial positive charge.
- Methods of Preparation
This part of the chapter discusses the methods of preparation of alkyl and aryl halides from different starting materials. Alcohols are converted to alkyl halides by replacing the alcoholic group by different halogens by using different halogen-containing reagents such as phosphorus halides, sodium halides, thionyl chloride etc.
Further, the chapter tells you about the synthesis of alkyl halides by free radical halogenation of hydrocarbons. Aryl chlorides and bromides can be prepared by an electrophilic substitution reaction of arenes with respective halogens. Sandmeyer’s reaction converts aryl amines to aryl halides.
This portion tells you next about using alkene to obtain alkyl halides by adding hydrogen halides/halogens to the double bond of an alkene. Fluorides and iodides are often prepared by various halogen exchange methods.
- Physical Properties
This part of the chapter discusses the physical properties of haloalkanes which are colourless in their pure state and some have a sweet smell. These are slightly soluble in water but soluble fully in organic solvents. Halogen containing organic compounds show higher boiling points compared to the corresponding hydrocarbons because of strong dipole-dipole and van der Waals forces of attraction.
- Chemical Reactions
This part of the chapter teaches you about the chemical reactions of haloalkanes and haloarenes.
- Reactions of haloalkanes
Due to the polarity in C-X bond, the haloalkanes show nucleophilic substitution reaction, elimination reactions and reaction with metals. This part further tells you that nucleophilic substitution reactions proceed through two different reaction mechanisms, depending upon their kinetic properties, substitution nucleophilic bimolecular (SN2) and substitution nucleophilic bimolecular (SN1).
This portion also tells you that chirality of products obtained helps in understanding the reaction mechanisms of SN1 and SN2 reactions in chiral alkyl halides, the SN1 mechanism being characterised by racemisation whereas the SN2 mechanism by inversion of configuration. Also, the order of reactivity of alkyl halides towards SN2 increases in the order tertiary halide < secondary halide < primary halide < CH3X. For SN1, it is exactly the other way.
This portion also elaborately discusses the reaction of alkyl halides with metals to give organometallic compounds, which contain C-M bonds.
Reactions of haloarenes
This part of the chapter tells you that aryl halides are extremely less reactive towards nucleophilic substitution reactions because of the resonance effect prevailing in the benzene ring and difference in hybridisation state of a carbon atom. They undergo replacement of halogen atoms by a hydroxyl group, electrophilic substitution reaction at ring carbon atoms and reaction with metals.
- Polyhalogen Compounds
This part of the chapter introduces you to the carbon compounds containing more than one halogen atom, called polyhalogen compounds. Some of the polyhalogen compounds, e.g., DDT, freon, dichloromethane, chloroform, iodoform and carbon tetrachloride, have many industrial uses. Some of these compounds cannot be decomposed easily and cause depletion of the ozone layer proving to be environmental hazards.
CBSE NCERT Class 12 Chemistry Chapter 10 Exercise
Our NCERT Solutions for Class 12 Chemistry Chapter 10 – Haloalkanes and Haloarenes consist of answers to all 22 questions of the exercise covering the important topics learnt in this chapter. The constituents of the exercise have been listed below.
- Questions 1 and 2 are based on IUPAC nomenclature of compounds.
- Question 3 asks you to convert names to the structure.
- Questions 4 and 5 ask you to apply the concepts learnt in this chapter.
- Question 6 asks you to draw the isomers.
- Question 7 is based on the preparation of Iodobutane.
- Question 8 is a direct question asking about ambident nucleophiles.
- Question 9 is a reasoning question.
- Question 10 is an applicative question based on elimination.
- Questions 11 and 19 ask you about the reaction conditions to bring about chemical conversions.
- Questions 12 and 18 are explanatory questions.
- Question 13 asks about uses of polyhalogen compounds.
- Questions 14 and 22 ask you to predict the products of given reactions.
- Questions 15 and 20 are based on the mechanism of nucleophilic substitution/elimination reaction.
- Question 16 asks you to arrange the compound according to their reactivity towards SN2 reactions.
- Question 17 is based on the reactivity difference of alkyl and aryl halides.
- Question 21 is a sequence wise word problem on reactions of alkyl halides.
There are 9 intext questions asked in CBSE NCERT Solutions for Class 12 Chemistry Chapter 10 to which accurate, easy to understand and step by step answers are provided in our solutions. These questions are in addition to the main questions asked at the end and provide an additional scope of practice to you.
Benefits of NCERT Solutions for Class 12th Chemistry Chapter 10 – Haloalkanes and Haloarenes
Some of the major benefits of referring Haloalkanes and Haloarenes are as follows –
- They help you build a strong conceptual foundation of the reaction mechanisms and their stereochemical implications.
- As organic chemistry is based on facts which need to be remembered at plenty of instances, our solutions give you tips and techniques to learn faster, better and improve your retention rate.
- They are a handy study source of all the principles covered in this chapter for effective revision during exams.
- They give you a fair idea of the types of questions asked in various exams and contain the best ways to solve the same.
They help you score well in your class 12th board exams by keeping your concepts clear always.