1. CHEMISTRY 3.5 ANSWERS
WORKSHEET SIX ORGANIC CHEMISTRY Amines
1. (a) Ethylamine and aminoethane (b) Pentylamine and 1-aminopentane
2. If the nitrogen atom is bonded to three carbons it is a tertiary amine. If the
nitrogen is bonded to two carbons it is a secondary amine and if the nitrogen
is bonded to only one carbon it is a primary amine.
3. (a) aminomethane / methylamine (1e) (b) dimethylamine (2e)
(c) trimethylamine (3e) (d) ethylmethylamine (2e)
(e) diethylmethylamine (3e) (f) aminoethane / ethylamine (1e)
Alcohol/NH3
4. CH3CH2Cl CH3CH2NH2
5. For primary and secondary amines, the presence of the N-H bond enables the
amine molecules to hydrogen bond to water molecules. This allows them to
dissolve in water. With higher Mr this solubility decreases.
6. Although both primary amines and alcohols can form hydrogen bonds to
each other, the hydrogen bonding in alcohols is stronger than in amines as O
is more electronegative than N and so the boiling point is higher..
7. Amines are stronger bases than ammonia.
8. (a) CH3CH2NH2 + H2O  CH3CH2NH3+(aq) + OH-(aq)
(b) (CH3CH2)2NH + H2O  (CH3CH2)2NH2+(aq) + OH-(aq)
(c) (CH3CH2)3N + H2O  (CH3CH2)3NH+(aq) + OH-(aq)
9. (a) CH3CH2NH3+ + H2O  CH3CH2NH2 + H3O+
(b) The pH of the solution in (a) will be acidic as the ethylammonium ion
acts as a weak acid donating a proton to the water molecules.
10. (a) CH3CH2NH2 + HCl(aq) → CH3CH2NH3+(aq) + Cl-(aq)
(b) 2(CH3CH2)2NH + H2SO4 (aq) → 2(CH3CH2)2NH2+(aq) + SO42-(aq)
(c) (CH3CH2)3N + HNO3(aq) → (CH3CH2)3NH+(aq) + NO3-(aq)
(d) 2CH3NH2 + H2SO4(aq) → 2CH3NH3+(aq) + SO42-(aq)
11. (a) ethylammonium chloride
(b) diethylammonium sulfate
(c) triethylammonium nitrate
(d) methylammonium sulfate