10 Alkanes

Question 1

CH₂CH₂ → CH₃CH₃

Answer 1

Reduction:
H₂, [ Ni, heat / Pt / Pd ]

Question 2

CHCH → CH₃CH₃

Answer 2

Reduction:
H₂, Ni / Pt / Pd, heat

Question 3

CH₃CH₃ → CO₂ + H₂O

Answer 3

Complete combustion:
Excess O₂, burn

Question 4

CH₃CH₃→ CH₃CH₂X + HX

Answer 4

FRS Halogenation (Mono-substitution):
Limiting X₂, UV light / heat
Decolourisation of greenish-yellow Cl₂ / reddish-brown Br₂
Formation of white HCl / HBr fumes that turn damp blue litmus paper red

Question 5

CH₃CH₃→ CX₃CX₃ + HX

Answer 5

FRS Halogenation (Poly-substitution):
Excess X₂, UV light / heat
Decolourisation of greenish-yellow Cl₂ / reddish-brown Br₂
Formation of white HCl / HBr fumes that turn damp blue litmus paper red

Question 6

Reactivity of Alkanes

Answer 6

Generally unreactive:
1. Lack of electron-rich / electron-deficient regions to attract electrophiles / nucleophiles
2. Relatively strong C–C and C–H bonds with high bond energies

Question 7

Functional group of Alkanes

Answer 7

C–C