Carboxylic acids are a series of organic acids defined by the carboxyl functional group, with a general formula and varying properties such as boiling points and solubility. They exhibit weak acid behavior and undergo reactions with metals, carbonates, bases, and alcohols to form salts, water, and gases. Esters, formed through the reaction of carboxylic acids and alcohols during esterification, are colorless and used in perfumes and food flavorings.

2. CARBOXYLIC ACIDS
• Carboxylic acids are a homologous series of organic acids which have the carboxyl (-COOH)
functional group
• They have the general formula CnH2n+1COOH

3. CARBOXYLIC ACIDS
Name Molecular formula Structural formula Full structural formula
methanoic acid HCOOH HCOOH
ethanoic acid CH3COOH CH3COOH
propanoic acid C2H5COOH CH3CH2COOH
butanoic acid C3H7COOH CH3CH2CH2COOH

4. PHYSICAL PROPERTIES OF CARBOXYLIC
ACIDS
Acid Boiling point /0C
methanoic acid 101
ethanoic acid 118
propanoic acid 141
butanoic acid 164
• The above carboxylic acids are all soluble in water.
• Boiling point increases as the molecular size increases.

5. CHEMICAL PROPERTIES OF CARBOXYLIC
ACIDS
• Carboxylic acids are weak acids because they ionise only partially in aqueous solution.
• ethanoic acid ⇌ ethanoate ion + hydrogen ion
• CH3COOH(aq) ⇌ CH3COO-(aq) + H+(aq)
⇌ + H

6. CHEMICAL PROPERTIES OF CARBOXYLIC
ACIDS
• Reaction with reactive metals
• carboxylic acid + metal  salt + hydrogen
• ethanoic acid + magnesium  magnesium ethanoate + hydrogen
• 2CH3COOH(aq) + Mg(s)  (CH3COO)2Mg(aq) + H2(g)

7. CHEMICAL PROPERTIES OF CARBOXYLIC
ACIDS
• Reaction with carbonates
• carboxylic acid + carbonate  salt + carbon dioxide + water
• ethanoic acid + sodium carbonate  sodium ethanoate + carbon dioxide + water
• CH3COOH(aq) + Na2CO3(aq)  2CH3COONa(aq) + CO2(g) + H2O(l)

8. CHEMICAL PROPERTIES OF CARBOXYLIC
ACIDS
• Reaction with bases
• carboxylic acid + bases  salt + water
• ethanoic acid + sodium hydroxide  sodium ethanoate + water
• 2CH3COOH(aq) + NaOH(aq)  CH3COONa(aq) + H2O(l)

9. CHEMICAL PROPERTIES OF CARBOXYLIC
ACIDS
• Reaction with alcohols

10. PRODUCING ETHANOIC ACID
• Oxidation by acidified potassium manganate (VII)
• ethanol + oxygen from oxidising agent + heat  ethanoic acid + water
• CH3CH2OH(aq) + 2[O] + heat  CH3COOH(aq) + H2O(l)
2+  + H2O

11. PRODUCING ETHANOIC ACID
• Oxidation by atmospheric oxygen
• ethanol + oxygen from air + bacteria  ethanoic acid + water
• CH3CH2OH(aq) + O2(g) + bacteria  CH3COOH(aq) + H2O(l)

12. ESTERS
• A sweet smelling compound called esters.
• An ester is a colourless liquid that is insoluble in water. The function group is:

13. ESTERS
• Esters are formed by the reaction of a carboxylic acid with an alcohol. This reaction is known as
esterification.

14. ESTERIFICATION
• Ethanoic acid is warmed with ethanol in the presence of a
few drops of sulfuric acid, water and an ester called ethyl
ethanoate are formed. Concentrated sulfuric acid acts as a
catalyst for the reaction.

15. ESTERIFICATION
• ethanoic acid + ethanol + concentrated sulfuric acid ⇌ ethyl ethanoate + water
• CH3COOH(aq) + C2H5OH(aq) + H2SO4(aq) ⇌ CH3COOC2H5(aq) + H2O(l)
• During the formation of ethyl ethanoate, the –OH group from ethanoic acid is replaced by the
CH3-CH2-O- group from ethanol.

16. ESTERIFICATION

17. NAMING ESTERS
Reactants Ester formed
Acid Alcohol
methanoic acid
(HCOOH)
ethanol
(C2H5OH)
ethyl methanoate
(HCOOC2H5)
ethanoic acid
(CH3COOH)
methanol
(CH3OH)
methyl ethanoate
(CH3COOCH3)
ethanoic acid
(CH3COOH)
ethanol
(C2H5OH)
ethyl ethanoate
(CH3COOC2H5)
The name of an ester consist of two parts. The first part is derived from the alcohol, the second part is derived
from the carboxylic acid.

18. USES OF ESTERS
• Esters are used in perfumes, as artificial food flavourings and as solvents for cosmetics and
glues.

19. • Permission is granted to you for personal use only. Contact
admin@basecamp.sg for commercial or school usage.