crude oil/ cracking

Question 1

crude oil

Answer 1

is a mixture of hydrocarbons

Question 2

fossil fuel

Answer 2

formed of dead remains of plants and animals
non renewable
eg coal, natural gas, oil

Question 3

hydrocarbon

Answer 3

a compound that only contains hydrogen and carbon
( simple covalent molecules)

Question 4

refining crude oil

Answer 4

big mixture of different compounds isn’t useful so is refined
separated by fractional distillation

Question 5

fraction

Answer 5

mixture of hydrocarbon molecules with a similar no. carbons (similar chain lengths) and similar bp.

Question 6

oil fractions order

Answer 6

refinery gases
gasoline
kerosene
diesel
fuel oil
bitumen

Question 7

process of fractional distillation

Answer 7

• crude oil is heated and enters fractionating column as a vapour
• column is cooler at top and warmer at bottom
• vapours rise up column once hydrocarbon cools to a temp below bp it condenses
• hydrocarbons with lower bp are nearer top creating fractions

Question 8

use of refinery gases

Answer 8

bottles gas

Question 9

use of gasoline

Answer 9

car fuel

Question 10

use of kerosene

Answer 10

aircraft fuel

Question 11

use of diesel

Answer 11

fuel in diesel engines

Question 12

use of fuel oil

Answer 12

fuel for ships power stations

Question 13

bitumen

Answer 13

for roads and roofs

Question 14

viscosity

Answer 14

how easily something flows

Question 15

volatility

Answer 15

how easily something vaporises

Question 16

flammability

Answer 16

how easily something burns/ ignites

Question 17

boiling point trend

Answer 17

increases as you go down

Question 18

viscosity trend

Answer 18

increases as you go down (from runny to thick)

Question 19

volatility trend

Answer 19

decreases as you go down

Question 20

flammability trend

Answer 20

decreases as you go down

Question 21

colour trend

Answer 21

darker as you go down

Question 22

size trend

Answer 22

get bigger as you go down

Question 23

why must sulphur impurities be removed

Answer 23

when you burn an impure fuel SO2 will be made which causes acid rain and pollution

Question 24

what is cracking

Answer 24

the thermal decomposition of large hydrocarbons (alkanes) into smaller (alkanes + alkenes) that are more useful

Question 25

why is cracking important

Answer 25

long chain are in lower demand/use - large surplus
short chain are in larger demand/ use but low supply
so long are cracked into smaller more useful to meet demand

Question 26

cracking in the lab

Answer 26

wool soaked in paraffin (gentle heat) and a catalyst (strong heat) is heated in a boiling tube
gas is made and collected over water

Question 27

suck back

Answer 27

remove delivery tube before stopping hearing to prevent this

Question 28

catalyst in cracking

Answer 28

silica or alumina

Question 29

temperature of cracking

Answer 29

600-700°C

Question 30

purpose of wool

Answer 30

to absorb liquid and keep it at end of tube

Question 31

why is mineral wool gently heated

Answer 31

to vapourier it but prevent it combusting

Question 32

why are pottery fragments strongly heated

Answer 32

as gas molecules hit hot catalyst they break up into smaller molecules
strong heat prevents suckback