P1 4b crude oil

Question 1

what is crude oil?

Answer 1

mixture of different hydrocarbons

Question 2

what are fractions?

Answer 2

groups of hydrocarbons in crude oil that are of similar chain lengths

Question 3

how do you separate the fractions in crude oil?

Answer 3

fractional distillation

- in each fraction the hydrocarbons have similar boiling points and properties

Question 4

what do the fractions mainly contain?

Answer 4

alkanes

Question 5

how is fractional distillation carried out?

Answer 5

by a fractionating column

• very hot at the bottom, cool at the top
• crude oil enters and is heated so the vapours rise
• vapours with high boiling points will condense into liquid at the higher temperatures lower down the column
• and vise versa

Question 6

where are the fractions containing smaller hydrocarbons collected?

Answer 6

at the top of the fractionating column as gases

Question 7

where are the fractions containing bigger hydrocarbons collected?

Answer 7

at the lower parts as liquids

Question 8

where does the temp decrease in the fractionating column?

Answer 8

as you move up the temperature decreases

Question 9

what are the properties of crude oil?

Answer 9

viscosity
- ease of flow of a liquid
- higher viscosity liquids are thick and don’t flow easily
colour
- as the chain length increases the colour gets darker
melting/boiling points
- as the molecules get larger the intermolecular attractions becomes greater, so more heat is needed to separate the molecules
volatility
- the tendency to vaporise
- with increasing molecular size hydrocarbons they become less volatile

Question 10

what are the main fractions in crude oil?

Answer 10

refinery gases 
petrol
kerosene 
diesel 
fuel oil 
bitumen

Question 11

what are refinery gases used for?

Answer 11

domestic heating and cooking

Question 12

what is petrol used for?

Answer 12

fuel for cars

Question 13

what is kerosene used for?

Answer 13

jet fuel

Question 14

what is diesel used for?

Answer 14

diesel engines

Question 15

what is heavy fuel oil used for?

Answer 15

ships and power stations?

Question 16

what is bitumen used for?

Answer 16

surfacing roads and roofs

Question 17

what are the products from combusting fuels?

Answer 17

burning of fossil fuels produces carbon dioxide, carbon monoxide, oxides of nitrogen, oxides of sulphur

Question 18

what are the difference in products produced in incomplete and complete combustion?

Answer 18

complete 
- water 
- carbon dioxide 
incomplete 
- unburnt fuel (soot)
- carbon monoxide 
- water

Question 19

what are the dangers of carbon monoxide?

Answer 19

causes dizziness, loss of consciousness and can be fatal

• CO binds to haemoglobin
• prevents it from binding to O2 and CO2

Question 20

how are nitrogen oxides formed?

Answer 20

when N and O react in high pressure and temperature conditions of internal combustion engines and blast furnaces

Question 21

what are catalytic converters?

Answer 21

in cars exhaust systems
contain a series of transition metal catalysts
- catalysts are in a honeycomb to increase surface area

Question 22

how do catalytic converters work?

Answer 22

redox reactions occur which neutralises the pollutant gases

- carbon monoxide is oxidised to carbon dioxide

Question 23

what are the transition metals used in catalytic converters?

Answer 23

platinium and rhodium

Question 24

how does sulphur dioxide form?

Answer 24

combustion of fossil fuels
- fossil fuel often contain sulphur impurities
when sulphur in the fuels get oxidised it creates sulphur dioxide

Question 25

what are the effects of sulphur dioxide?

Answer 25

acid rain
- causes corrosion to metal structures, buildings, carbonate rocks and aquatic organisms
pollutes crop and water supply
irritates lungs, throats, and eyes

Question 26

what contributes to acid rain?

Answer 26

sulphur and

nitrogen oxides

Question 27

how is acid rain formed?

Answer 27

• sulphuric acid from sulphur in hydrocarbons

- nitrogen dioxide from car engines

Question 28

what is a saturated molecule?

Answer 28

when it contains single bonds only

Question 29

what is a unsaturated molecule?

Answer 29

when it contains double bonds between carbon atoms

Question 30

what is cracking?

Answer 30

a process used to convert long chain molecules into short chain molecules that are more useful

Question 31

what are the two ways to crack?

Answer 31

catalytic and steam cracking

Question 32

what is the process of catalytic cracking?

Answer 32

• heating hydrocarbons to 470-550C to vaporise them
• the vapours then pass over a hot powdered catalyst of aluminium oxide
• it breaks covalent bonds causing thermal decomposition

Question 33

what is the outcome of catalytic cracking?

Answer 33

produces a mixture of smaller alkanes and alkenes

Question 34

why is cracking useful?

Answer 34

it increases the supply of particular fractions
- which supplies the demand
smaller hydrocarbons have a higher demand than supply, this is the opposite for fuel oil and bitumen

Question 35

what type of reaction is cracking?

Answer 35

endothermic reaction