Crude oil

Question 1

what is crude oil?

Answer 1

a complex mixture of hydrocarbon only

Question 2

how are the molecules of crude oil?

Answer 2

it gas molecules in which carbon atoms are in chain or rings

Question 3

why is crude oil an important substance?

Answer 3

because it is the fuels and feedstock for the petrochemical industry

Question 4

is crude oil renewable?

Answer 4

no, it is a finite resource that will eventually run out one day

Question 5

describe how the industrial process of fractional distillation separates crude oil into fractions

Answer 5

1. oil is heated in the fractioning column and the oil evaporates and condenses at a number of different temperatures
2. the many hydrocarbons in crude oil can be separated into fractions each which contains molecules with a similar number of carbon atoms
3. the fractioning column works continuously. Heated oil is piped in at the bottom. The vaporised oil rises up the column and the various fractions are constantly tapped off at the different levels where they condense
   - the fractions can be processed to produce fuels and feedstock for the petrochemical industry

Question 6

what are the names of the main fractions obtained from crude oil?

Answer 6

• refinery gases
• gasoline/ petro
• kerosene
• diesel
• fuel oil
• bitumen

Question 7

what is refinery gases used for?

Answer 7

domestic heating and cooking

Question 8

what is gasoline/ petrol used for?

Answer 8

fuel for cars

Question 9

what is kerosene used for?

Answer 9

fuel for aircraft

Question 10

what is diesel used for?

Answer 10

fuel for some cars and trains

Question 11

what is fuel oil used for?

Answer 11

fuel for large ships and in some power stations

Question 12

what is bitumen used for?

Answer 12

surfaces roads and roofs

Question 13

what properties influence crude oil’s influence as fuels?

Answer 13

some properties of hydrocarbon which depend on the size of their molecules

Question 14

what properties influence crude oil’s influence as fuels?

-> the shorter the molecule

Answer 14

• the lower the temperature at which that fraction vaporises or condenses
• the lower its boiling point
• the less viscous it is

Question 15

in longer molecules where are colours darker?

Answer 15

at the bottom fractions

Question 16

what is fuel?

Answer 16

a substance that releases heat energy when burned

Question 17

what is produced in complete combustion?

Answer 17

CO1 and H2O

Question 18

what is produced in incomplete combustion?

Answer 18

if there is not enough oxygen some fuels don’t burn. Here carbon monoxide and unburnt fuels are released

Question 19

why is carbon monoxide dangerous?

Answer 19

it prevents red blood cells carrying oxygen around the body. This can lead to breathing difficulties and eventually death

Question 20

temperatures in car engines are reached high enough to allow what?

Answer 20

nitrogen and oxygen from air to reach forming oxides of nitrogen

Question 21

what is produced when fuels are burnt?

Answer 21

the sulfur is oxidised to produce sulfur dioxide

Question 22

what happens when sulfur and oxides of nitrogen are emitted into the atmosphere?

Answer 22

they react with rain water to create H+ acids

Question 23

what happens when acid rain falls?

Answer 23

• the acid can ruin rocks and buildings

- can also alter the pH in soil or rivers which can affect an ecosystem

Question 24

what are long chain alkanes converted to in cracking?

Answer 24

alkenes and shorter chain of alkanes

Question 25

why are long chain alkanes converted into smaller molecules?

Answer 25

they are cracked into smaller molecule because they are more useful. This process involves heating the hydrocarbon to vaporise them

Question 26

what are alkenes?

Answer 26

unsaturated hydrocarbons

Question 27

why is cracking necessary

Answer 27

because the demand for smaller chained alkanes is much greater than for longer chained alkanes