# Aldehydes, Ketones and Carboxylic Acids Notes | SwaVid Aldehydes, Ketones and Carboxylic Acids, NCERT Class 12 Chemistry: notes with key ideas, formulas, common mistakes and 3 quick checks with worked answers. Canonical: https://www.swavid.com/cbse/class-12/chemistry/chapter/aldehydes-ketones-and-carboxylic-acids Source: https://www.swavid.com/cbse/class-12/chemistry/chapter/aldehydes-ketones-and-carboxylic-acids # Aldehydes, Ketones and Carboxylic Acids ## Formulas and definitions ## Key ideas ## Common mistakes ## Quick checks ## Keep going ## Questions parents ask ## Class 12 Chemistry on SwaVid ### Structure of carbonyl group ### Preparation of aldehydes and ketones ### Nucleophilic addition reactions ### Oxidation and reduction reactions ### Reactions due to alpha-hydrogen ### Structure and acidity of carboxylic acids ### Reactions of carboxylic acids ### Next chapter ### Related chapter ### Related chapter ### All chapters SwaVid › CBSE › Class 12 › Chemistry › Aldehydes, Ketones and Carboxylic Acids Notes written by SwaVid from the NCERT textbook. Class 12 Chemistry, Unit 8. Key ideas, formulas and common mistakes. CBSE prints 8 marks for Unit 8, not for this chapter alone. Short answer. This chapter covers the preparation, physical properties, and chemical reactions of carbonyl compounds and carboxylic acids. Students learn how nucleophilic addition reactions distinguish aldehydes and ketones, while resonance stabilisation governs the acidity of carboxylic acids. Source: NCERT Chemistry Part II (Reprint 2026-27) , Unit 8, Aldehydes, Ketones and Carboxylic Acids The carbonyl carbon is sp² hybridised and forms three σ bonds in a planar trigonal arrangement. The carbon-oxygen double bond is polar because oxygen is more electronegative, giving electrophilic character to carbon and nucleophilic character to oxygen. Aldehydes are prepared by controlled oxidation of primary alcohols, dehydrogenation, Rosenmund reduction of acyl chlorides, and Stephen reaction of nitriles. Ketones are obtained by oxidation of secondary alcohols, hydration of alkynes, Friedel-Crafts acylation, and the reaction of nitriles with Grignard reagents. Aldehydes are generally more reactive than ketones towards nucleophiles due to less steric hindrance and weaker electron-donating inductive effects. Reagents such as HCN, NaHSO₃, alcohols, and ammonia derivatives (NH₂-Z) add across the carbonyl double bond. Aldehydes easily oxidise to carboxylic acids with mild oxidising agents such as Tollens' reagent and Fehling's solution. Ketones resist mild oxidation but undergo reduction to hydrocarbons via Clemmensen reduction (Zn-Hg / HCl) or Wolff-Kishner reduction (NH₂NH₂ / KOH / ethylene glycol). The α-hydrogens of aldehydes and ketones are acidic due to the electron-withdrawing carbonyl group and resonance stabilisation of the conjugate base. This acidity enables aldol condensation in compounds with α-hydrogens, whereas compounds lacking α-hydrogens undergo the Cannizzaro reaction with concentrated alkali. Carboxylic acids contain a carboxyl group where the carbonyl group is linked to a hydroxyl group. Carboxylate ions are resonance-stabilised with negative charge shared equally between two electronegative oxygen atoms, making carboxylic acids more acidic than phenols and alcohols. Carboxylic acids form anhydrides on heating with P₂O₅, esters with alcohols in acid medium, and amides through ammonium carboxylate intermediates. They undergo α-halogenation via the Hell-Volhard-Zelinsky (HVZ) reaction and lose carbon dioxide on heating sodium salts with soda lime. Try each question first. Then tap it to see the answer. Identify steric and electronic factors: aldehydes have less steric hindrance and only one alkyl group donating electron density to the carbonyl carbon compared to ketones. Propanal is an aldehyde and is more reactive than both ketones. Between propanone (CH₃COCH₃) and butanone (CH₃COCH₂CH₃), butanone has a larger ethyl group causing greater steric hindrance and stronger +I effect. Order of increasing reactivity: butanone Cl > H, so fluorine exerts the strongest -I effect and chlorine exerts a stronger -I effect than hydrogen. Stronger -I effect stabilises the carboxylate anion more effectively. Order of increasing acid strength: ethanoic acid < chloroethanoic acid < fluoroethanoic acid. ethanoic acid < chloroethanoic acid < fluoroethanoic acid Amines . Alcohols, Phenols and Ethers . Haloalkanes and Haloarenes . The 10 chapters of Class 12 Chemistry . CBSE does not give marks to one chapter. It prints 8 marks for Unit 8, Aldehydes, Ketones and Carboxylic Acids, which includes Aldehydes, Ketones and Carboxylic Acids. No. They are written by SwaVid from the NCERT textbook. The CBSE curriculum is the reference for what is assessed. Amines. SwaVid is an AI tutor for Indian students in Classes 6 to 12. It finds the earlier ideas a child missed, then teaches today’s chapter. Start free to see how it works. - Unit 8 NCERT book - 8 marks, Unit 8 - 3 quick checks - Using Fehling's test to detect aromatic aldehydes like benzaldehyde . Fehling's solution oxidises aliphatic aldehydes only. Use Tollens' reagent instead, as it oxidises both aliphatic and aromatic aldehydes. - Predicting aldol condensation for methanal or benzaldehyde . Aldol condensation requires at least one α-hydrogen atom. Since methanal and benzaldehyde lack α-hydrogens, they undergo the Cannizzaro reaction in strong base instead. - Assuming electron-donating groups increase carboxylic acid acidity . Electron-donating groups destabilise the carboxylate anion by intensifying negative charge and decrease acidity. Electron-withdrawing groups stabilise the anion through the -I effect and increase acidity. - Writing Clemmensen reduction conditions for acid-sensitive compounds . Clemmensen reduction uses concentrated HCl, which attacks acid-sensitive groups. Use Wolff-Kishner reduction instead, which operates under basic conditions. ## Key Links - [CBSE](https://www.swavid.com/cbse) - [Class 12](https://www.swavid.com/cbse/class-12) - [Chemistry](https://www.swavid.com/cbse/class-12/chemistry/chapters) - [Start free →](https://www.swavid.com/signup) - [All 10 chapters](https://www.swavid.com/cbse/class-12/chemistry/chapters) - [NCERT Chemistry Part II (Reprint 2026-27)](https://ncert.nic.in/textbook.php) - [Open notes](https://www.swavid.com/cbse/class-12/chemistry/chapter/amines) - [Open notes](https://www.swavid.com/cbse/class-12/chemistry/chapter/alcohols-phenols-and-ethers) - [Open notes](https://www.swavid.com/cbse/class-12/chemistry/chapter/haloalkanes-and-haloarenes) - [Class 12 Chemistry](https://www.swavid.com/cbse/class-12/chemistry/chapters) - [Start free →](https://www.swavid.com/signup)