4. b. Crude oil

Question 1

definition of crude oil

Answer 1

mixture of hydrocarbons

Question 2

what method is used to separate crude oil

Answer 2

factional distillation

Question 3

describe how fractional distillation separates crude oil into fractions

( rhyme = Only Grab The Tapas Lovely Soldier )

Answer 3

1. oil heated = most turned into gas
2. gases enter a fractionating column - liquid bitumen = drained of at the bottom
3. temp gradient in fractionating column = hot at bottom + gradually gets cooler as you go up
4. temp = lower than boiling point = substances condense
5. long hydrocarbons = high boiling point = condense + drain out early near bottom
6. Shorter Hydrocarbons = low boiling point = condense + drain out near top

Question 4

what are the fractionating column products

rhyme = Ravenous Pigs Keenly Devour Lettuce For Breakfast

Answer 4

Refinery Gases 
Petrol 
Kerosene 
Diesel 
Lubricating Oil
Fuel heavy oil
Bitumen

Question 5

uses of fractions

Answer 5

Refinery Gases = domestic heating +cooking
Petrol =- car fuel
Kerosene = plane fuel
Diesel = lorry / train fuel
Lubricating Oil =
Fuel heavy oil = Ship fuel ( + some power stations)
Bitumen = tarmacking roads

Question 6

definition of a fuel

Answer 6

substance that when burned releases energy

Question 7

what are the products of complete combustion of hydrocarbons with oxygen in air

Answer 7

carbon dioxide + water

Question 8

what are the products of incomplete combustion of hydrocarbons with oxygen in air

Answer 8

carbon dioxide + water + carbon monoxide

Question 9

why is carbon monoxide poisonous

Answer 9

can combine with haemoglobin in red blood cells and stop blood from carrying oxygen around the body

Question 10

what does the high temp in car engines do

Answer 10

allow nitrogen + oxygen from air to react = oxides of nitrogen ( nitrogen monoxide + nitrogen dioxide )

Question 11

what does the combustion of some impurities in hydrocarbons result in

Answer 11

sulphur dioxide

Question 12

what is the danger of sulphur dioxide + nitrogen oxides

Answer 12

contribute to acid rain

when sulphur dioxide + nitrogen oxides mix with water vapour in clouds = dilute sulphuric acid + nitric acid = acid rain

Question 13

how are long-chain alkanes converted to alkenes and shorter-chain alkanes

Answer 13

catalytic cracking

Question 14

definition for cracking

Answer 14

splitting up long chain hydrocarbons

form of thermal decomposition ( breaking molecules down into simpler molecules by heating them.

Question 15

what are the conditions required for cracking

Answer 15

catalyst = silica or alumina
heat = 600-700*c

Question 16

how is cracking carried out in industry

Answer 16

1. vaporised hydrocarbons are passed over a powered catalyst ( silica / alumina ) at about 600-700*c
2. alkane heated up till vaporised = break down when comes into contact with catalyst = produce mixture of shorter-chain alkanes + alkenes

Question 17

why is cracking necessary

Answer 17

demand for shorter-chain hydrocarbons ( eg. octane in petrol) is much higher than for longer-chain hydrocarbons

to meet demand ( + achieve balance of supply & demand ) long chain hydrocarbons are split into more useful short-chain molecules

Question 18

what are the properties of long-chain hydrocarbons ( boiling point + viscosity + colour )

Answer 18

boiling point = high
viscosity = viscous = thick + gloopy
colour = darker

Question 19

what are the properties of shorter-chain hydrocarbons ( boiling point + viscosity + colour )

Answer 19

boiling point = low
viscosity = thinner
colour = paler