Alkanes

Question 1

Properties of alkanes

Answer 1

1) Insoluble in water
2) Flammable (decreases down the group)
3) Melting and boiling point increases down the group

Question 2

What type of hybridisation is there in alkanes?

Answer 2

sp3

Question 3

Substitution of alkanes with halogens

Answer 3

Type of reaction: free radical substitution
Condition: u.v light

Question 4

What are the products produced during complete combustion and colour of flame?

Answer 4

Carbon dioxide and water
Blue

Question 5

What are the products of incomplete combustion and colour of flame?

Answer 5

Carbon (soot, black), carbon monoxide and water
Yellow

Question 6

What is the cracking of alkanes and condition?

Answer 6

Cracking is the process by which long chains of alkanes are broken down into smaller alkanes, alkenes and hydrogen
Condition: heat with Al2O3

Question 7

Explain the lack of reactivity in alkanes

Answer 7

The electronegativity difference between C and H atoms is very small therefore the bonds are non-polar. Thus alkanes do not attract electrophiles or nucleophiles for reactions to occur. The C-H bond is quite strong and requires a large amount of energy to break.

Question 8

Reactions that produce alkanes (2)

Answer 8

1) Cracking
2) Addition of H to an alkene