fractional distillation

Question 1

what does petroleum consist of?

Answer 1

Petroleum is a mixture consisting mainly of alkane hydrocarbons that can be separated by fractional distillation.

Question 1

what is crude oil?

Answer 1

a mixture of different length hydrocarbons

Question 2

what is unique about the fractionating column?

Answer 2

the column has a temperature gradient. it is cooler at the top as the vapour rises. parts of the mixture condense at different temperatures.

Question 3

why do different hydrocarbons condense at different temperatures?

Answer 3

different chain lengths means difference in boiling points.

the fractions are drawn off at different levels

Question 4

what is the fractionating columns temperature gradient?

Answer 4

cool at the top and hot at the bottom

Question 5

how does boiling point change as hydrocarbon lengths increases?

Answer 5

boiling point increases as hydrocarbons get longer

Question 7

what temperature is crude oil vapourised at in the furnace?

Answer 7

350 degrees celcius

Question 8

what happens to vaporised crude oil as it enters the column?

Answer 8

oil enters the column and rises through trays

the longest hydrocarbons dont vaporise and run down to the bottom of the column

Question 9

what happens to shortest hydrocarbons in the fractionating column?

Answer 9

the shortest hydrocarbons wont even condense at 20 degrees and comes off as a gas at the top of the column

Question 10

what is the order of fractions in the column? starting from the top of the column and going downwards

Answer 10

gas

gasoline (petrol)

kerosene

diesel

fuel oil

bitumen

Question 11

What are the gases from fractional distilation used for ?

Answer 11

used in LPG and stove gas

Question 12

what is kerosine used for?

Answer 12

jet fuel and heating

Question 13

what is petrol used for?

Answer 13

used in petrol cars

Question 14

what is diesel oil used for?

Answer 14

used as diesel fuel

Question 15

what is fuel oil used for?

Answer 15

used in ships and power stations

Question 16

what is bitumen used for ?

Answer 16

used in roofing and tarmac

Question 17

what is cracking?

Answer 17

breaking a longer chain alkane into shorter hydrocarbons

Question 18

why do we crack longer chain alkanes?

Answer 18

to break them into shorter hydrocarbons that have higher demand e.g petrol

Question 19

what are the conditions for thermal cracking?

Answer 19

high temp and pressure

1000 degrees celcius
70 atm pressure

Question 20

what is the pressure used in thermal cracking?

Answer 20

70atm

Question 21

what is the temperature used in thermal cracking ?

Answer 21

1000 degrees celcius

Question 22

what are the products of thermal cracking?

Answer 22

mainly alkenes

Question 23

what are alkenes used to make?

Answer 23

polymers such as plastic

Question 24

what is propene used to make ?

Answer 24

poly(propene)

Question 25

what are the conditions for catalytic cracking?

Answer 25

high temperature and slight pressure used.
temperature = 450 degrees celcius

zeolite catalyst which lowers the temperature needed

Question 26

what catalyst is used in catalytic cracking?

Answer 26

zeolite

Question 27

what temperature is used in catalytic cracking?

Answer 27

450 degrees celcius

Question 28

what does the zeolite catalyst do?

Answer 28

lowers the temperature and pressure needed for cracking to occur

this lowers costs and speeds up the process

Question 29

what are the products of catalytic cracking?

Answer 29

aromatic hydrocarbons- useful in fuels for vehicles

Question 30

what are aromatic compounds?

Answer 30

contain benzene rings which is 6 carbons in ring with a delocalised electron system

Question 31

what are aromatic hydrocarbons useful for?

Answer 31

useful in fuels for vehicles