NCERT Solutions for Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids
NCERT Solutions for Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids provides answers to all the questions asked in this chapter. Our NCERT Solutions explains the class of compounds known as aldehydes, ketones and carboxylic acids, their structures, IUPAC nomenclature, and methods of preparation and reactions. This chapter also tells you how to correlate the structures of aldehydes, ketones and carboxylic acids with their physical and chemical properties. In this chapter, you will also learn about various aspects related to the acidity of carboxylic acids and their reactions. This chapter also describes the uses of aldehydes, ketones and carboxylic acids.
In this chapter, there are a total of 20 questions asked at the end. All of these questions fully cover all the concepts taught in NCERT CBSE Class 12 Chemistry Chapter 12. The questions asked are direct, explanatory, about predicting reagent, reactant or product of a chemical reaction. These are based on characteristics of carbonyl group, preparation and properties of aldehydes, ketones and carboxylic acids, all the reactions shown by aldehydes and ketones, acidity of carboxylic acids and reactions shown by carboxylic acids. This is a very important unit in class 12 chemistry.
All of these questions have been answered accurately in Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids. The solutions follow all the guidelines given by CBSE and NCERT. They are easy to understand, accurate and to the point. They have been drafted in a manner to help you learn more effectively.
NCERT Class 12 Chemistry Chapter 12
NCERT Solutions for Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids include all the topics of this chapter. They give you a comprehensive understanding of all the topics and subtopics covered in this chapter. The main topics covered in this chapter are as follows.
- Nomenclature and Structure of Carbonyl Group
This part of the NCERT Class 12 Chemistry Chapter 12 tells you that aldehydes and ketones are compounds containing a >C=O group which is polar in nature. They can have their names from two systems, common names and IUPAC names. Rules guiding the nomenclature are given in this portion of the chapter. Hybridisation in the carbonyl carbon atom is sp2, and its structure is planar. Also, the C=O bond is polarised due to the high electronegativity difference between oxygen and carbon.
- Preparation of Aldehydes and Ketones
This part of the CBSE NCERT Class 12 Chemistry Chapter 12 tells you the methods of preparing these compounds. Here you will learn that Aldehydes are prepared by controlled oxidation or dehydrogenation of primary alcohols, and ozonolysis of alkenes. Acyl halides can be selectively reduced to aldehydes in controlled conditions.
This part of the chapter further tells you that aromatic aldehydes can be prepared by oxidising methylbenzene with chromyl chloride or CrO3 in the presence of (CH3CO)2O, formylation of arenes with CO and HCl in the presence of anhydrous AlCl3/Cu2Cl2, and by hydrolysis of benzal chloride.
Also, here you will come to know that ketones are prepared by oxidation of secondary alcohols and hydration of alkynes. Ketones are also prepared by reaction of an acyl chloride with dialkyl cadmium or by Friedel Crafts acylation of aromatic hydrocarbons with acyl chlorides/anhydrides. Ketones can also be prepared by ozonolysis of alkenes.
- Physical Properties
This part of the NCERT CBSE Class 12 Chapter 12 discusses the physical properties of aldehydes and ketones. These have high boiling points compared to hydrocarbons and weakly polar compounds of comparable molecular masses. The lower members are more soluble in water as they can form hydrogen bonds with water whereas for higher members, the large size of the hydrophobic chain of carbon atoms outweighs, and they become insoluble in water but they are soluble in common organic solvents.
- Chemical Reactions
This part of the CBSE NCERT Class 12 Chapter 12 tells you that both the aldehydes and ketones contain the same functional group, carbonyl group. Hence they show similar chemical reactions. Both aldehydes and ketones undergo nucleophilic addition reactions at the carbonyl group with a number of nucleophilic reagents like alcohols, NH3, HCN, NaHSO3, Grignard’s reagent.
This chapter tells you that α-hydrogens in aldehydes and ketones are acidic and the aldehydes and ketones having at least one α -hydrogen, in the presence of a base, undergo Aldol condensation to give α – hydroxy aldehydes and α – hydroxy ketones respectively. Aldehydes which do not have an α-hydrogen give Cannizzaro reaction under similar conditions.
This chapter also teaches you that Aldehydes and Ketones undergo reduction with reducing agents like metal hydrides to give corresponding alcohols. They can also be reduced to alcohols by catalytic hydrogenation. The carbonyl group of aldehydes and ketones can be reduced to a methylene group by Wolff-Kishner reduction and Clemmensen reduction. Aldehydes can be distinguished by using mild oxidising reagents like Tollen’s reagent or Fehling’s reagent. Aldehydes get oxidised to carboxylic acids whereas ketones are not with these reagents. Through relevant examples, this chapter talks about how Aldehydes and ketones find their use in a number of industries as solvents, starting materials and reagents.
- Carboxylic acids
In this part, you will learn about carboxylic acids. They are usually known by common names, and there are rules to give them IUPAC names as well. The carboxylic carbon is less electrophilic than carbonyl carbon as there is a resonance between the two oxygen atoms of the carboxylic group.
You further learn here that carboxylic acids are prepared by oxidation of alkenes, aldehydes and primary alcohols. They are also prepared by hydrolysis of nitriles, and by treating Grignard reagents with CO2. Aromatic carboxylic acids are obtained when side-chains of alkylbenzenes are oxidised. Reduction of carboxylic acids to primary alcohols is carried out with LiAlH4 or with B2H6 in ether solution. A characteristic reaction of carboxylic acids containing α-hydrogens is HVZ reaction in which they undergo α-halogenation with halogens in the presence of red P.
Here you will also learn that carboxylic acids are significantly acidic compared to alcohols and phenols. The carboxylic acids such as formic acid, acetic acid and benzoic acid are highly useful compounds in industry.
CBSE NCERT Class 12 Chemistry Chapter 12 Exercise
Our NCERT Solutions for Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids consists of 20 questions covering the important topics learnt here. The components of the exercise have been listed below.
- Question 1 asks you to describe the chemical term and example of a related reaction.
- Questions 2 and 4 are based on the IUPAC nomenclature.
- Question 3 asks to convert names into structures.
- Questions 5, 6, 9, 10 and 11 ask you to predict the product of the given reaction and draw the structure of the product.
- Question 7 is based on Aldol and Cannizzaro reactions.
- Questions 8, 14 and 15 ask you to indicate the reaction conditions for given conversions.
- Question 12 asks you to arrange the compounds in order of given property.
- Question 13 asks you to distinguish between a pair of compounds through chemical tests.
- Question 16 is a direct question asking you to describe the terms.
- Question 17 asks you to predict the missing starting material, reagent or product.
- Questions 18 and 20 are explanatory questions.
- Question 19 is a sequential question on chemical reactions asking for a product, the intermediates and products.
There are 8 intext questions asked in CBSE NCERT Class 12 Chemistry Chapter 12 to which best answers have been provided in our solutions.
Benefits of NCERT Solutions for Class 12th Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids
The process of learning and revising from NCERT Solutions for Class 12 Chemistry Chapter 12 – Aldehydes, Ketones and Carboxylic Acids is highly beneficial for you. Some of the advantages are as follows.
- They are easy to understand as they are written in a simple language.
- They are all-encompassing yet to the point solutions providing the best way to learn and remember the concepts.
- They are a hundred percent accurate so are reliable.
- They make the process of learning interesting and efficient and ensure timely usage of topics learnt.
They help you to achieve higher marks in class 12th board exams and prepare for the competitive exams you are planning to take in the future.