Chapter 12 Alkanes

Question 1

What state are alkanes with chain length C₁ - C₄

Answer 1

Gases

Question 2

What state are alkanes with chain length C₅ - C₁₆

Answer 2

Colourless liquids

Question 3

What state are alkanes with chain length C₁₇ +

Answer 3

White Waxy Solids

Question 4

As chain length increases does the B.P. Increase or decrease and why

Answer 4

Increases
* As chain length increases, molecules have a larger surface area
* More surface contact is possible between molecules
* London forces between molecules will be greater
* More energy required to overcome them

Question 5

As Branching increases does BP increase or decrease and why

Answer 5

Decreases
* As branching increases, there are fewer surface points of contact,
leading to fewer London forces
* Branching increases, molecules can’t get as close together as straight
chains, leading to weaker London forces
* Less energy required to overcome them

Question 6

In a limited, not extremely limited supply what products are formed from the combustion of alkanes

Answer 6

Carbon Monoxide
Water

Question 7

In an extremely limited supply what products are formed from the combustion of alkanes

Answer 7

Carbon
Water

Question 8

What condition is required for alkanes to react with halogens (Cl₂) or Br₂)

Answer 8

UV light or sunlight

Question 9

When an alkane is reacted with a halogen what is the colour change and observed change on litmus paper

Answer 9

red-brown —> Colourless

Litmus paper turns red