Dr James Chemistry SPM Form 5 Chapter 2 Carbon Compounds

1.  Carboxylic acids are weak acid
 General Formula:
 Functional Group:
 Naming of carboxylic acid:
CnH2n+1COOH
Carboxyll
Number
of Carbon
1 2 3 4 5 6
Molecular
formula
HCOOH CH3COOH C2H5COOH C3H7COOH C4H9COOH C5H11COOH
Name
methanoic
acid
ethanoic
acid
propanoic
acid
butanoic
acid
pentanoic
acid
hexanoic
acid
n = 0, 1, 2, ...
Carboxylic Acids

2. Physical
Properties of
Carboxylic
Acids
Colour
- Colourless
liquid
State
- Larger molecules
(C10 above) are
wax-like solids
Odour
- sharp/
unpleasant smell
Boiling point
- High boiling
point
Solubility
- Simple molecules
are very soluble in
water
- Due to water
molecule being
strongly attracted to
the – COOH group
- Solubility ↓ when
number of C ↑

3.  Alcohols can be oxidised to carboxylic acids
using potassium dichromate(VI) solution in
the presence of dilute sulphuric acid.
 Chemical Equation below represent the
reaction.
C2H5OH+ 2[O] → CH3COOH + H2O
Preparing Carboxylic Acids

4. Alcohols can be
oxidised to produce
carboxylic acid
when react with
oxidising agents

5. a. Acid properties
 CH3COOH is a weak monoprotic acid
 Only one hydrogen atom can ionize in water to
produce H+ ion
 Partially dissociate in water
 Turn moist blue litmus → red
 React slowly with metals, bases and carbonates
CH3COOH ↔ CH3COO- + H+
Ethanoic acid Ethanoate ion
Chemical Properties Of Carboxylic Acids

6. b. Reaction with metals
 Carboxylic acid + metal → salt + H2
c. Reaction with carbonates
 Carboxylic acid + carbonates → salt + CO2 + H2O
2CH3COOH + Zn → Zn(CH3COO)2 + H2
Ethanoic acid Zinc ethanoate
2CH3COOH + CaCO3 → Ca(CH3COO)2 + CO2 + H2O
Ethanoic acid Calcium ethanoate

7. d. Reaction with bases
 Carboxylic acid + bases → salt + H2O
CH3COOH + NaOH → CH3COONa + H2O
Ethanoic acid Sodium ethanoate
2CH3COOH + CuO → Cu(CH3COO)2 + H2O
Ethanoic acid Copper (II) ethanoate

8. e. Reaction with alcohols (esterification)
 Carboxylic acid + alcohol → ester + H2O
 Catalyst: Concentrated H2SO4
CH3COOH + C4H9OH → CH3COOC4H9 + H2O
Ethanoic acid Butan-1-ol Buthyl ethanoate

9.  Ethanoic acid (acetic acid)
• As a flavouring
• As a preservative
• Used with other chemicals to make drugs, dyes,
paints, insecticides and plastics
 Methanoic acid (formic acid)
• Used to coagulate latex
 Fatty acids (long-chain carboxylic acids)
• Used in making soaps
 Benzoic acid
• Preservative in food
Uses of Carboxylic Acids