sc20, fuels (paper 2)

Question 1

what is a crude oil

Answer 1

a fossil fuel formed over millions of years from ancient remains of marine organisms

Question 2

define hydrocarbon

Answer 2

compounds of carbon and hydrogen atoms ONLY

Question 3

what are the different possible bonds in a hydrocarbon molecule

Answer 3

• carbon __ carbon bonds
• carbon __ hydrogen bonds

Question 4

what are the two things hydrocarbon molecules can consist of

Answer 4

• chains (with or without branches)
• rings of carbon atoms

Question 5

what is a finite resource

Answer 5

• no longer being made or
• being made extremely slowly

Question 6

why are sources from crude oil useful

Answer 6

• hydrocarbons are useful as fuels
• and as feedstock for the petrochemical industry

Question 7

define feedstock

Answer 7

starting material for an industrial chemical process

Question 8

define petrochemical industry

Answer 8

involves the use and manufacture of substances from crude oil

Question 9

why can you use fractional distillation to seperate crude oil into simpler, more useful mixtures

Answer 9

the different hydrocarbons have different boiling points

Question 10

what is a fraction in terms of crude oil

Answer 10

a mixture of hydrocarbons with similar boiling points and number of carbon atoms

Question 11

what happens to the gas fraction in fractional distilaltion for crude oil

Answer 11

doesn’t condense and leaves at the top

Question 12

what happens to the bitumen fraction in fractional distilaltion for crude oil

Answer 12

doesn’t evaporate and leaves at the bottom

Question 13

what happens to the ‘other’ fraction in fractional distilaltion for crude oil

Answer 13

they are liquid at room temp and are useful as fuels

Question 14

true or false: most hydrocarbons are alkanes

Answer 14

true

Question 15

true or false: most hydrocarbons are alkenes

Answer 15

false

Question 16

what happens as the number of carbon and hydrogen atoms in a hydrocarbon molecule increase

Answer 16

• the strength of the intermolecular forces increases
• more energy must be transfered to overcome these forces
• the boiling point increases

Question 17

what is an alkane

Answer 17

form a homologous series of hydrocarbons

Question 18

what is a homologous series

Answer 18

a series of compounds:
- in which molecular formulae of neighbouring members differ by CH2
- that show a gradual variation in physical properties
- that have similar chemical properties

Question 19

what happens when alkanes undergo complete combustion

Answer 19

they form carbon dioxide and water vapour

Question 20

what do alkanes end in

Answer 20

ane

Question 21

why does incomplete combustion happen

Answer 21

when the supply of oxygen to a burning fuel is limited

Question 22

what happens in complete combustion

Answer 22

• hydrogen is oxidised to water vapout
• carbon is oxidised to carbon dioxide
• energy is transferred to surroundings by radiation as heat and light

Question 23

what happens in incomplete combustion

Answer 23

• carbon may be partially oxidised to carbon dioxide, CO
• carbon may be released at carbon particles or soot
• less energy is given out

Question 24

in combustion, what depends on how much carbon is produced

Answer 24

how much oxygen is available for oxidation

Question 25

why is carbon monoxide bad

Answer 25

- attaches to haemoglobin in red blood cells - preventing oxygen from attaching - reducing th eoxygen carries around the body by bloodstream

Question 26

what two things makes carbon monoxide hard to detect

Answer 26

- colourless - odourless

Question 27

how can we detect gas

Answer 27

electronic carbon monoxide detectors

Question 28

why is soot bad

Answer 28

- builds up in chimneys where it may eventually cause fires and blacken buildings - tiny soot particles may cause lung diseases such as bronchitis - or make existing lung diseases worse

Question 29

what is acid rain

Answer 29

rain more acidic than usual

Question 30

how is acidic rain made

Answer 30

when sulfur dioxide or oxides of nitrogen dissolves in water in the air

Question 31

how is sulfur dioxide created in the atmosphere

Answer 31

- hydrocarbon fuels contain impurities of sulfur compounds - when the fuel burns, the sulfur in these impurities are oxidsed - to form sulfur dioxide

Question 32

how are oxides of nitrogen created in the atmosphere

Answer 32

- air goes inside to engine so the fuel can burn - nitrogen and oxygen from the air react together at high tempuratures - in the engine to produce oxides of nitrogen

Question 33

what can acid rain do to our environment

Answer 33

- speeds up the weathering of buildings and statues - damages trees - acidifies rivers, lakes, sails - which harms organisms livin gin them

Question 34

how can we reduce problems caused by acid rain

Answer 34

- remover sulfur from fueks before selling - 'flue gas desulfurisation' - preventing sulfur dioxide leaving power station chimneys - adding calcium carbonate/hydroxide to fiels and lakes to neutralise excess acid from acid rain

Question 35

what else, other than petrol or diesel oils, can be used for cars

Answer 35

hydrogen

Question 36

list the fossil fuels obtained from crude oil

Answer 36

- petrol - deisel oil - fuel oil

Question 37

what is petrol used in

Answer 37

cars

Question 38

what is diesel oil used in

Answer 38

cars and trains

Question 39

what is fuel oil used in

Answer 39

large ships and power stations

Question 40

true or false: fossil fuels are non renewable

Answer 40

true

Question 41

true or false: fossil fuels are renewable

Answer 41

false

Question 42

what is a non renewable resource

Answer 42

resources used up faster than they are formes

Question 43

give the symbol equation for the combustion of hydrogen

Answer 43

2 H2 + O2 --> 2 H2O

Question 44

how can hydrogen be manufactures

Answer 44

- electrolysis of water - cracking of oil fractions - reaction of natural gas with steam

Question 45

give the symbol equation for the reaction of natural gas with steam

Answer 45

CH4 (g) + 2 H2O (g) --> CO2 (g) + 4 H2 (g)

Question 46

what are the qualities of a good fuel

Answer 46

- burn easily (easy to ignite and stay alight) - not produce soot, smoke, or ash - release a lot of energy when it burns - easy to store and transport safely

Question 47

pros of petrol

Answer 47

- burns easily - doesn't produce ash - a liquid (easy to store and transport) - releases more enrgy per kg than coal or wood

Question 48

cons of petrol

Answer 48

- produces carbon dioxide, monoxide and water

Question 49

pros of hydrogen as a fuel

Answer 49

- burns easily - doesn't produce ash or smoke - only produces water - releases 3x more energy than petrol

Question 50

cons of hydrogen as a fuel

Answer 50

- gas (hard to store, at high temps) - filling stations have to be adapted

Question 51

what is cracking

Answer 51

a process carried out on fractions in oil refineries after fractional distillation

Question 52

what is a summarized version of cracking

Answer 52

breaking down larger alkanes into smaller, more useful alkanes (for fuels) and alkenes (for polymers)

Question 53

true or false: paraffin is an alkene

Answer 53

false

Question 54

true or false: paraffin is an alkane

Answer 54

true

Question 55

descrube how paraffin can be cracked

Answer 55

- the polous pot catalyst is heated strongly - liquid paraffin is heated and evaporates - paraffin vapour passes over the hot porous pot and the hydrocarbon molecules break down - one of the products is thene (gas) and collects in the other tube