NCERT Exemplar Solutions for Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids

As a student in Class 12, you may be looking for reliable and comprehensive solutions to the questions in your Chemistry NCERT textbook. The NCERT Exemplar Solutions for Chemistry Class 12, Chapter 12 are designed to provide you with just that.

These Chemistry Class 12 Chapter 12 solutions have been created by subject specialists to offer thorough and easy-to-understand answers to all the unsolved questions from the textbook’s exercises. By practicing these solutions, you can enhance your conceptual knowledge and prepare effectively for entrance exams like JEE Mains Exam and NEET Exam.

The NCERT Exemplar solutions for Chapter 12 Class 12 Chemistry are written in a student-friendly language, making them accessible and easy to follow. The approaches used in solving the questions have been carefully considered to ensure that you stay on track without straying from the intended answer. This is particularly important in exams, where time management is crucial for achieving the best results.

By using these NCERT Exemplar Solutions for Chemistry Class 12 Chapter 12 Exercise, you can not only perform well in your Class 12 exams but also strengthen your foundation for upcoming competitive examinations. The solutions are designed to be both informative and engaging, helping you to learn and understand the concepts with ease.

Also Check – NCERT Solutions for Class 12 Chemistry

NCERT Exemplar Class 12 Chemistry Chapter 12 Aldehydes, Ketones and Carboxylic Acids PDF

Get ready to ace your Class 12 Chemistry exams with our comprehensive PDF on Aldehydes, Ketones, and Carboxylic Acids. This chapter covers the key concepts, including IUPAC names, structures, physical properties, and chemical reactions. Download now and boost your understanding of these crucial organic compounds.

Chemistry_Class12_Chapter12(DE-122)

Class 12 Chemistry Chapter 12 Aldehydes, Ketones and Carboxylic Acids Questions Answers

Preparing for your Class 12 Chemistry exams? Don’t miss the important questions and answers from Chapter 12 on Aldehydes, Ketones and Carboxylic Acids. Our experts have carefully selected the crucial topics to help you focus your studies and do well in your tests. Practice these questions to strengthen your understanding of the key concepts.

Ques. What is the general formula for aldehydes and ketones?

Ans: The general formula for aldehydes is RCHO, where R can be an alkyl group or hydrogen. The general formula for ketones is RCOR’, where R and R’ can be alkyl groups.

Ques. Explain the mechanism of the nucleophilic addition-elimination reaction in aldehydes and ketones.

Ans: The mechanism involves the following steps:

1. Nucleophilic addition of the nucleophile to the carbonyl carbon
2. Formation of a tetrahedral intermediate
3. Elimination of the leaving group (usually water) to regenerate the carbonyl group

Must See! – CBSE Class 12 Chemistry Syllabus

Ques. How do you distinguish between aldehydes and ketones using chemical tests?

Ans: Aldehydes can be distinguished from ketones using the Tollens’ test and the Fehling’s test. Aldehydes undergo oxidation in these tests, while ketones do not.

Ques. Write the IUPAC names of the following compounds:

a) CH3CHO

b) CH3COCH3

c) CH3CH2COOH

Ans:

a) Acetaldehyde

b) Acetone

c) Propanoic acid

Ques. Explain the effect of substituents on the acidity of carboxylic acids.

Ans: Electron-withdrawing substituents (e.g., halogens, nitro group) increase the acidity of carboxylic acids by stabilizing the conjugate base. Electron-donating substituents (e.g., alkyl groups) decrease the acidity by destabilizing the conjugate base.

Ques. How can you convert an aldehyde into a carboxylic acid?

Ans: Aldehydes can be oxidized to carboxylic acids using mild oxidizing agents like Tollens’ reagent or Fehling’s solution.

Ques. Explain the mechanism of the esterification reaction between a carboxylic acid and an alcohol.

Ans: The mechanism involves the following steps:

1. Protonation of the carboxylic acid to form a carbocation
2. Nucleophilic attack by the alcohol on the carbocation
3. Elimination of water to form the ester

Ques. What are the uses of carboxylic acids in everyday life?

Ans: Carboxylic acids have various uses in everyday life, such as:

• Acetic acid (vinegar) is used in cooking and as a preservative.
• Citric acid is found in citrus fruits and is used as a flavoring agent and preservative.
• Benzoic acid and its salts are used as food preservatives.
• Salicylic acid is used in skincare products and as a pain reliever.

Ques. Explain the structure and bonding in the carboxylate ion.

Ans: In the carboxylate ion, the carbon-oxygen bonds are of equal length, indicating resonance stabilization. The negative charge is delocalized between the two oxygen atoms, making the carboxylate ion a stable and important functional group.

Ques. How can you convert a carboxylic acid into an alcohol?

Ans: Carboxylic acids can be reduced to alcohols using a strong reducing agent like lithium aluminum hydride (LiAlH4).

Ques. Discuss the reactivity of aldehydes and ketones towards nucleophilic addition reactions.

Ans: Aldehydes and ketones are susceptible to nucleophilic addition reactions due to the electrophilic nature of the carbonyl carbon. Nucleophiles, such as water, alcohols, and amines, can add to the carbonyl group, forming tetrahedral intermediates that then eliminate a leaving group to regenerate the carbonyl.

Ques. Explain the mechanism of the Cannizzaro reaction.

Ans: The Cannizzaro reaction is a disproportionation reaction that occurs when an aldehyde without an α-hydrogen is treated with a strong base. The mechanism involves:

1. Deprotonation of the aldehyde to form an alkoxide ion
2. Nucleophilic attack of the alkoxide ion on another aldehyde molecule
3. Elimination of the alkoxide ion to form an alcohol and a carboxylate ion

Ques. Discuss the importance of carboxylic acids in biological systems.

Ans: Carboxylic acids play a crucial role in biological systems:

• Fatty acids are carboxylic acids that are the building blocks of lipids, which are important for cell membranes and energy storage.
• Amino acids, the building blocks of proteins, contain a carboxylic acid group.
• Citric acid and other carboxylic acids are intermediates in the Krebs cycle, a key metabolic pathway for energy production.
• Vitamins like ascorbic acid (vitamin C) and nicotinic acid (vitamin B3) are carboxylic acids.

Ques. Explain the mechanism of the Grignard reaction with aldehydes and ketones.

Ans: The Grignard reaction involves the following steps:

1. Reaction of a Grignard reagent (RMgX) with an aldehyde or ketone to form a tetrahedral intermediate
2. Protonation of the intermediate to form an alcohol

Ques. How can you convert a carboxylic acid into an acid chloride?

Ans: Carboxylic acids can be converted to acid chlorides by reaction with thionyl chloride (SOCl2) or oxalyl chloride ((COCl)2). This reaction involves the replacement of the hydroxyl group with a chlorine atom.

Chapter 12 – Aldehydes, Ketones and Carboxylic Acids

This chapter is covered in Term II of the CBSE Syllabus 2024 25. Aldehydes, ketones, and carboxylic acids are carbonyl compounds, which are very important in organic chemistry.

Aldehydes and ketones can be made by:

• Ozonolysis of alkenes
• Hydration of alkynes
• Oxidation of alcohols or cyanides

Carboxylic acids are obtained by:

• Oxidation of primary alcohols or aldehydes

Carboxylic acids are more acidic than alcohols or phenols because of resonance stabilization. These solutions are very useful for getting good marks and revising this chapter.

What You’ll Learn

By studying this chapter, you’ll be able to:

• Write IUPAC names and common names of ketones, aldehydes, and carboxylic acids
• Understand the structures, including compounds containing carbonyl and carboxyl functional groups
• Learn about the physical properties and chemical reactions of aldehydes, ketones, and carboxylic acids
• Explore the various factors that affect the acidity of carboxylic acids and their reactions

Subtopics of Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids

1. Nomenclature and Structure of Carbonyl Group
2. Preparation of Aldehydes and Ketones
3. Physical Properties
4. Chemical Reactions
5. Uses of Aldehydes and Ketones
6. Nomenclature and Structure of Carboxyl Group
7. Methods of Preparation of Carboxylic Acids
8. Physical Properties
9. Chemical Reactions
10. Uses of Carboxylic Acids

NCERT Exemplar Chemistry Class 12 Chapters 12 FAQs

What is the purpose of the NCERT Exemplar Solutions for Class 12 Chemistry Chapter 12?

The NCERT Exemplar Solutions provide detailed, step-by-step answers to all the questions from the exercises in the Class 12 Chemistry textbook chapter on Aldehydes, Ketones and Carboxylic Acids. They help students strengthen their conceptual understanding and problem-solving skills.

How do the NCERT Exemplar Solutions differ from the textbook solutions?

The Exemplar Solutions go beyond just providing answers - they explain the concepts, the reasoning, and the step-by-step workings in a more detailed and student-friendly manner compared to the textbook solutions. This helps students learn the material more effectively.

What topics are covered in the NCERT Exemplar Solutions for Chapter 12?

The solutions cover a wide range of topics from the chapter, including the properties and reactions of aldehydes, ketones, and carboxylic acids, mechanisms of important reactions, and the applications of these organic compounds.

How can students use the NCERT Exemplar Solutions to prepare for exams?

By practicing the Exemplar Solutions, students can identify their strengths and weaknesses, improve their problem-solving abilities, and get a good grasp of the important concepts and formulas needed to excel in their Class 12 Chemistry exams.