Alkanes

Question 1

Fractional distillation (crude oil separation)

Answer 1

Mixture is vaporised and put into fractionating column

Vapours rise, cool and condense

Products are used for different things

Products with short carbon chains move to the top - lower boiling points

Question 2

Types of cracking and definitions

Answer 2

Thermal cracking - produced high proportions of alkanes and alkenes. High temp and pressure crack the carbon chains to make then smaller

Catalytic cracking - lower temp and normal pressure used but a catalyst is needed to compensate for less harsh conditions

Question 3

Chlorination of alkanes
(3 steps)

Answer 3

Initiation:
Cl2 —UV—> 2Cl•

Propagation:
Cl• + CH4 —> •CH3 + HCl
•CH3 + Cl2 —> CH3Cl + Cl•

Termination :
•CH3 + •CH2 —> C2H6

Question 4

Chlorination of alkanes condition

Answer 4

UV light

Question 5

Why are long carbon chains broken down

Answer 5

When smaller they are more usedful

Question 6

What is produced in the combustion of alkanes (when undergoing complete combustion in O2)

Answer 6

CO2 and H2O

Question 7

Catalytic converters function

Answer 7

Removes gaseous products
- carbon monoxide (toxic)
- oxides of nitrogen (byproduct)

Catalytic converters use a rhodium catalyst to convert harmful products into more stable products e.g. CO2 or H2O