NCERT Solutions for Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes

The chapter Haloalkanes and Haloarenes in Class 12 Chemistry is an very important part for students who are preparing for cbse class 12 board exams. This topic explain the structure, properties, reactions and uses of compounds that contain halogen atoms. To help students understand better, NCERT solutions for class 12 chemistry haloalkanes and haloarenes are provided in a step–by–step and simple method. These class 12 ncert solutions are also helpful for solving textbook questions, preparing class 12 notes, and for practicing before exam.

The NCERT solutions class 12 chemistry chapter 10 haloalkanes and haloarenes gives detailed answers to Intext and Exercise questions that make concepts easy to remember. Along with this, many students search for NCERT for class 12 chemistry haloalkanes and haloarenes pdf so they can download and revise even without books. For strong exam prepration, students should also try MCQs on haloalkanes and haloarenes class 12 since multiple-choice questions are frequently asked in competitive tests like NEET and JEE.

By using NCERT solutions for class 12 chemistry, students can clear their doubts, practice more and score high marks. These ncert solutions follow the latest CBSE syllabus guidelines, so they are one of the best resource for Class 12 students.

Chapter 10 Class 12 Chemistry Haloalkanes and Haloarenes PDF with Solutions

The chapter Haloalkanes and Haloarenes is an important part of Class 12 Chemistry syllabus. Students can use NCERT for class 12 chemistry haloalkanes and haloarenes pdf to study concepts in simple way and practice exercises. This chapter cover physical properties, chemical reactions, naming rules and uses of halo compounds, which are also useful in cbse class 12 board and entrance exams. With NCERT solutions for class 12 chemistry haloalkanes and haloarenes, learners can revise fast and also solve MCQs on haloalkanes and haloarenes class 12 easily.

Class 12 Chemistry Chapter 10 Haloalkanes and Haloarenes – Key Notes & Solutions

Haloalkanes and Haloarenes are an important part of Class 12 Chemistry syllabus. The main difference is that Haloarenes have aromatic rings (like benzene) while Haloalkanes don’t contain rings. Also, free-radical halogenation happens easily in haloalkanes but not possible in haloarenes. Another simple point, haloarenes usually have a pleasant or sweet smell, while most haloalkanes are almost odorless.

In haloalkanes, the C–X bond (Carbon–Halogen bond) is a polar bond. This happens because halogen atoms (like chlorine, bromine, iodine) are more electronegative than carbon. Due to this, halogen pulls the shared electrons towards itself, giving it a partial negative charge, while carbon becomes partial positive.

Some important halogen compounds that we study in this chapter are: Dichloromethane (CH₂Cl₂), Trichloromethane (Chloroform), Tetrachloromethane (CCl₄), Iodoform (CHI₃), Freons, and DDT. These are very common in daily life and industry, but some like DDT also cause harmful effect on environment.

Why NCERT Solutions for Haloalkanes and Haloarenes are Important?

• NCERT Solutions for Class 12 Chemistry Chapter 10 help students write right answers in CBSE exams.
• These answers are made by expert Chemistry teachers, so they follow logical explanation and simple steps.
• The solutions strictly follow CBSE Class 12 Board pattern, making them the best resource for exam revision.
• Students can also download the NCERT for Class 12 Chemistry Haloalkanes and Haloarenes PDF to study anytime.
• Practicing these NCERT solutions for Class 12 Chemistry improve concept clarity and answer writing speed.

Practice Questions for Haloalkanes and Haloarenes with Answers

Students can try these important questions from Chapter 10 for exams and practice:

1. How is Alkyl Chloride Prepared?

Ans: Alkyl chlorides are prepared by several methods, but some common processes are:

• Reaction with Chlorine Gas: Chlorination of alkanes, where chlorine (Cl₂) reacts with an alkane (R-H) under UV light or heat to form alkyl chloride and hydrogen chloride (HCl).
• From Alcohols (Substitution reaction): Alkyl chlorides can be prepared by reacting alcohols with hydrogen chloride (HCl) or thionyl chloride (SOCl₂). This is a nucleophilic substitution reaction.
• From Alkyl Halides via Dehydrohalogenation: An alkyl halide can be treated with a base like sodium hydroxide (NaOH), undergoing dehydrohalogenation to form alkyl chloride.

2. Explain the Finkelstein Reaction

Ans: The Finkelstein reaction is a substitution reaction where an alkyl halide (R-Cl or R-Br) reacts with sodium iodide (NaI) in acetone, leading to the exchange of halogens. The halide ion in the alkyl halide is replaced by the iodide ion (I⁻) from sodium iodide, resulting in the formation of an alkyl iodide. This reaction occurs due to the solubility of sodium chloride (NaCl) or sodium bromide (NaBr) in acetone, while sodium iodide (NaI) is insoluble, driving the reaction forward.

Example: R-Cl + NaI → R-I + NaCl

3. What Are Nucleophiles in Organic Reactions?

Ans: Nucleophiles are molecules or ions that donate a pair of electrons to form a new bond in a chemical reaction, especially in nucleophilic substitution or addition reactions. They are typically electron-rich species, and they attack electrophilic centers (often positively charged or partially positively charged atoms like carbon).

• Common nucleophiles include:
  • Halide ions (Cl⁻, Br⁻, I⁻)
  • Alcohols (R-OH)
  • Amines (NH₃, R-NH₂)
  • Hydroxide ions (OH⁻)

4. Define a Racemic Mixture with One Example

Ans: A racemic mixture is a mixture containing equal amounts of two enantiomers (optical isomers) of a chiral molecule. These enantiomers rotate plane-polarized light in opposite directions, canceling out each other's effects, resulting in no net optical activity for the mixture.

Example: The racemic mixture of 2-bromobutane consists of equal amounts of (R)-2-bromobutane and (S)-2-bromobutane, which are mirror images of each other.

5. Write Two Uses of Tetrachloromethane (CCl₄)

Ans: 

• Solvent in Cleaning and Degreasing: Tetrachloromethane (CCl₄), also known as carbon tetrachloride, is used as a solvent in cleaning agents and in the degreasing of metals in industry.
• Fire Extinguisher: It was previously used in fire extinguishers, particularly for electrical fires, as it is non-flammable and does not conduct electricity. However, its use has been restricted due to toxicity and environmental effects.

6. Describe the Fittig Reaction of Haloarenes

Ans: The Fittig reaction involves the synthesis of biaryl compounds (such as biphenyl) from haloarenes (aromatic halides) and alkali metals (like sodium or potassium) under dry conditions. This reaction results in the coupling of two aryl groups, replacing the halogen atom with another aryl group from a different molecule.

Example: C₆H₅Cl + C₆H₅Na → C₆H₅-C₆H₅ (Biphenyl)

7. What Do You Mean by Ambident Nucleophiles?

Ans: Ambident nucleophiles are species that can act as nucleophiles in two different ways, depending on which atom in the molecule provides the electron pair for bonding. They can attack at either one site or another within the molecule.

Example: Cyanide ion (CN⁻) is an ambident nucleophile because it can attack the electrophile via the carbon (C) or nitrogen (N) atom, forming different products depending on the attack site.

8. Mention One Use Each of DDT and Iodoform

Ans: 

• DDT (Dichlorodiphenyltrichloroethane): Used as a pesticide to control mosquito populations, particularly in the fight against malaria, though its use has been restricted due to environmental concerns.
• Iodoform (CHI₃): Used as an antiseptic, particularly for cleaning wounds, and as a disinfectant in medical applications.

9. What Product Forms When Ethyl Chloride Reacts with AgNO₂?

Ans: When ethyl chloride (C₂H₅Cl) reacts with silver nitrate (AgNO₂), it undergoes a nucleophilic substitution reaction, where the chloride ion (Cl⁻) is replaced by the nitro group (NO₂⁻). This produces ethyl nitrite (C₂H₅NO₂) and silver chloride (AgCl) as a by-product.

C₂H₅Cl + AgNO₂ → C₂H₅NO₂ + AgCl

10. How Do You Convert Chlorobenzene to 2-Chlorotoluene and Ethanol to Propanenitrile?

Ans: 

Converting Chlorobenzene to 2-Chlorotoluene:

This conversion involves the Friedel-Crafts alkylation reaction. Chlorobenzene is reacted with methyl chloride (CH₃Cl) in the presence of an aluminum chloride (AlCl₃) catalyst to introduce the methyl group at the ortho position to the chlorine atom.

C₆H₅Cl + CH₃Cl → 2-Chlorotoluene

Converting Ethanol to Propanenitrile:

Ethanol (C₂H₅OH) is first oxidized to acetaldehyde (CH₃CHO) using an oxidizing agent like PCC or KMnO₄. Then, the acetaldehyde is reacted with hydrogen cyanide (HCN) in the presence of a base to form propanenitrile (C₃H₅CN).

C₂H₅OH → CH₃CHO → C₃H₅CN

Conclusion

Class 12 Chemistry students are advised to practice MCQs on Haloalkanes and Haloarenes Class 12, short notes, and long-answer questions along with the NCERT exercises. The questions given in the NCERT solutions class 12 chemistry chapter 10 haloalkanes and haloarenes will help prepare with confident mindset for CBSE Class 12 board exam.