Carboxylic acids belong to a homologous series of organic compounds containing the carboxyl functional group (-COOH). They are weak acids that can react with bases to form salts, with reactive metals to form salts and hydrogen gas, and with carbonates to form salts, carbon dioxide and water. Ethanoic acid is an important carboxylic acid used to make vinegar. Esters are formed from a reaction between carboxylic acids and alcohols, and have a general formula of RCOOR'. Esters have sweet smells and flavors and are used in perfumes, foods, and solvents.

1. Carboxylic Acids

2. Let’s Recall

3. What areCarboxylic Acids?Belong to a homologous series of organic compounds similar to alkanes, alkenes and alcohols

4. The hydrocarbon chains contain the functional group -COOH (carbonyl group)Structural Formula Chemical FormulaCH3COOH orCH3CO2H =

5. Naming the Carboxylic AcidsMethanoicacid

6. Total of one carbon atom (meth-)

7. C0H1COOH

8. Ethanoicacid

9. Total of two carbons atoms (eth-)

10. C1H3COOH

11. Propanoicacid

12. Total of three carbon atoms (propan-)

13. C2H5COOH*Take note of the functional group’s location, highlighted by the dotted box

14. Naming Carboxylic AcidsH HH C C HH HH O H C C O HHReplace the ‘e’ with ‘oic acid’ at the end of the name of the hydrocarbon Example:ethanoic acidethane

15. Physical Properties ofEthanoic AcidsSimilar to its alcohol:

16. Colourless liquid at room temperature & relatively low boiling point of 118oC

17. Completely miscible(able to dissolve) in water

18. Has a characteristic ‘sour-ish’ smell

19. Is a weak acidof pH 3Are carboxylic acids the same as the acids we have learnt about in the chapter on acids and bases?Watch and observe!!It’s time to predict and discuss!

20. Video of demonstration

21. Chemical Properties of Carboxylic AcidsAs carboxylic acid is weak, its reactions produce the same outcomes as those learnt from the chapter of Acids, Bases and Salts

22. But, the reactions are less vigorousAcid PropertiesWeak acids(pH ≈ 3).Most of the acid molecules are unionised in water.For example: 1.0 mol/dm3 solution of ethanoic acid CH3COOH(aq) CH3COO(aq) + H+(aq)

23. Reaction with basesto form a salt and waterFor example:CH3COOH + NaOH CH3COONa + H2OAcid Properties

24. Reaction with reactivemetalsto form a salt and hydrogenFor example:2CH3COOH + Mg (CH3COO)2Mg + H2Acid Properties

25. Reaction with carbonatesto form a salt, carbon dioxide and waterFor example:2CH3COOH + Na2CO3 2CH3COONa + CO2 + H2OAcid Properties

26. Ethanoic acid is the most important organic acidIt is used in vinegar as preservative and flavourings.Uses of Carboxylic Acids

27. Other Important Organic Acids

28. Making of drugs, dyes, paints, insecticides, plastics.

29. Making of esters.Uses of Organic Acids