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NCERT Questions for Class 12 Chemistry Chapter 6 – Haloalkanes and Haloarenes
Chapter 6 of Chemistry for Class 12: Haloalkanes and Haloarenes is essential to comprehending the realm of organic molecules. By illuminating their structures, names, characteristics, and interactions, this chapter explores the fascinating realm of haloalkanes and haloarenes. A solid understanding of the underlying ideas and the capacity to successfully answer a range of questions are essential for success in this subject. By familiarizing yourself with the concepts and NCERT important questions related to this chapter, you can build a strong foundation for further studies in chemistry. Practising these questions and applying the concepts will help you to enhance your understanding.
Important Questions with Solutions of Class 12 Chemistry Chapter 6 – Haloalkanes and Haloarenes
1) Segregate the below points in increasing order properly as mentioned:
(i) bromomethane, chloromethane, dichloromethane. (Increasing order of boiling points).
Ans – As you know, the compounds mentioned are haloalkanes. The order goes like this,
Chloromethane < Bromomethane < Dichloromethane
As the size of the halogen increases, the boiling point also increases, and for the same chain with an increase in the number of halogen atoms, the boiling point will also increase.
(ii) 1-chloropropane, isopropyl chloride, 1-chlorobutane (Increasing order of boiling point)
Ans – On the mentioned compounds there is an availability of chlorine atoms, but the alkyl chain size is completely different. The order goes like this:
Isopropyl chloride < 1- Chloropropane < 1 – Chlorobutane
Since the chain size is branched, the boiling point will reduce and if the chain size increases, the boiling point will also increase.
(iii) dichloromethane, chloroform, and carbon terachloride. (Increasing order of dipole moment).
Ans – Here are the 3D structures of the 3 different compounds, along with the path of every bond’s dipole moment.
CCI4 has zero dipole moment due to its symmetrical nature. When 2 C-CI dipole moments are included in the CHCI3, the C-H & C-CI bonds repel each other. CHCI3 contains a modest dipole moment (1.03 D) due to the dipole moment of the 2nd resultant tends to be less than the first one. Hence, in CH₂CI₂, the resulting dipole moment of C-Cl pairs is more than in CHCI3. Since it contains a dipole moment, CH₂CI₂ will be a robust one.
Hence, the order goes like this:
Carbon tetrachloride < Chloroform < Dichloromethane
(iv) CH3F, CH3CI, CH3Br, CH3I (Increasing reactivity over Nucleophilic substitution & increasing order of dipole moment).
Ans – Such a reaction is called a nucleophilic substitution reaction if there is interaction between a nucleophile (an electron pair giver) using an electron pair acceptor.
We all know when one moves down the group, the element size increases. The larger the element is, the more likely it is to act as a leaving group and the sooner the possibility for the nucleophile to bond.
The sequence is shown as: CH3F < CH3CI < CH3Br < CH3I
(v) o,m.p-dichlorobenzenes as per increasing order of melting points
Ans – Since it possesses its symmetry and structure, p-dichlorobenzene has the highest melting point along with ortho & meta. The melting zone of a compound is based on its symmetry. Therefore, the order of the melting point will directly relate to the order of the symmetry of the compound.
It includes: m-Dichlorobenzene < o-Dichlorobenzen < p-Dichlorobenzene