Topic 8 - fuels and earth science

Question 1

what are hydrocarbons?

Answer 1

A compound that contains only carbon and hydrogen atoms

Question 2

what is crude oil?

Answer 2

• a complex mixture of hydrocarbon
• a important source of useful substances
• a finite source
• containing molecules in which carbon atoms are in chains or rings

Question 3

what is meant by a finite source?

Answer 3

the resource is no longer being made or being made extremely slowly

Question 4

what is crude oil separated into

Answer 4

-gases
-petrol
-kerosene
-diesel oil
-fuel oil
- bitumen

Question 5

explain the separation of crude oil through fractional distillation

Answer 5

• crude oil can be separated through fractional distillation as hydrocarbons have different boiling points
• oil is heated to evaporate it
• vapour rises up the fractionating coloumn
• each fraction condenses the gas where it becomes cool eneough and is piped out of that specific coloumn,
• due to a concentration gradient

-gases fraction do not condense and leave through the top
- bitumen does not evaporate

Question 6

what is the uses for gases

Answer 6

• domestic heating and cooking

Question 7

what is the uses for petrol

Answer 7

fuel for cars

Question 8

what is the uses for kerosene

Answer 8

fuel for aircraft

Question 9

what is the uses for diesel oil

Answer 9

fuel for some cars and trains

Question 10

what is the uses for fuel oil

Answer 10

fuel for large ships and some power stations

Question 11

what is the uses for bitumen

Answer 11

surfacing roads and roofs

Question 12

how do hydrocarbon in crude oil differ from each other

Answer 12

petrol ——-> bitumen
increases in carbon and hydrogen atoms
increase in boiling point
decrease in flammability
increase in viscosity ( from runny to thick)

Question 13

describe the complete combustion of hydrocarbons?

Answer 13

• produces carbon dioxide and water
• gives out energy
• methane + o2 = co2 + water

Question 14

why does incomplete combustion occur

Answer 14

a lack of supply of o2

Question 15

Explain why the incomplete combustion of hydrocarbons can produce carbon and carbon monoxide

Answer 15

• due to insufficient amount of o2
  -different carbon products form depending on the amount of 02 available such carbon monoxide or co2

Question 16

what is produced from incomplete combustion

Answer 16

methane + oxygen
——–>
carbon + carbon monoxide CO + carbon dioxide + water

Question 17

Explain how carbon monoxide behaves as a toxic gas

Answer 17

• binds with haemoglobin in red blood cell to stop o2 from circulating
• can cause death or unconsciousness
• colourless and odourless

Question 18

Describe the problems caused by incomplete combustion producing carbon monoxide and soot in appliances that use carbon compounds as fuels

Answer 18

• soot blocking pipes which carry waste gases away from appliances
• soot blackens building
  -soot can cause breathing problems
• carbon monoxide will bind to haemoglobin stopping the circulation of o2

Question 19

Explain how impurities in some hydrocarbon fuels result in the production of sulfur dioxide

Answer 19

• hydrocarbon may contain sulfur compounds
• when the hydrocarbon is burnt the sulfur reacts with oxygen to for sulfur dioxide gas

Question 20

Explain some problems associated with acid rain caused when sulfur dioxide dissolves in rainwater

Answer 20

• sulfur dioxide will dissolve into the water in clouds to form acid rain
• can cause increase of weathering against building made of limestone
• causes crops too not grow well due to acidic conditions
• can also kill and harm aquatic life
• increased rate of iron corrosion

Question 21

Explain why, when fuels are burned in engines, oxygen and nitrogen can react together at high temperatures to produce oxides of nitrogen, which are pollutants

Answer 21

• fuel is mixed with are in an engine
• the oxygen and nitrogen will react together due to the high temp in the engine
• causes the production of various oxides of nitrogen which are atmospheric pollutants

Question 22

Evaluate the advantages and disadvantages of using hydrogen, rather than petrol, as a fuel in cars

Answer 22

ad of using hydrogen
-only produces water no ash or smoke
- burns easy
- releases 3 times more energy per kg that petrol

dis of using hydrogen
- needs to be stored in high pressures so filling stations would need to change
- hydrogen is hard to store

Question 23

Recall that petrol, kerosene and diesel oil are non-renewable fossil fuels obtained from crude oil and methane is a non renewable fossil fuel found in natural gas

Answer 23

crude oil
-gas
-petrol
-bitumen
-diesel
-kerosene
-fuel oil

Natural gas
-methane
ethane

Question 24

explain the process of cracking

Answer 24

the breaking of covalent bonds in hydrocarbon molecules for a more desired product

eg - large alkanes broken into small alkane and alkenes (unsaturated)

Question 25

why is cracking necessary

Answer 25

to meet up with the demand of more used fuels as it is a finite resource

Question 26

describe earths early atmosphere

Answer 26

-little to no 02 - large amount of co2 - water vapour - small amounts of other gases

Question 27

what is the evidence for the early atmosphere

Answer 27

- lots of volcanic activity back then which is why there is a lot of co2 - the atmosphere of other planets having no organisms but volcanos also have lots of co2 and no o2 which is similar to early earth

Question 28

Explain how condensation of water vapour formed oceans

Answer 28

- the earth cooled down - water vapour condensed into water to form the ocean

Question 29

Explain how the amount of carbon dioxide in the atmosphere was decreased when carbon dioxide dissolved as the oceans formed

Answer 29

- water forms oceans - carbon dioxide dissolved in the oceans - marine organisms used the dissolved carbon dioxide to make calcium carbonate for shells - the shells of dead marine organisms fall to the sea bed and become part of sediment - it t is then squashed to form sedimentary rock - this reduces the amount of co2 in the atmosphere

Question 30

how does the growth of primitive plants increase the amount of o2 in the atmosphere

Answer 30

- earth cools and oceans form - forms of life evolve in the oceans and photosynthesis begins. - oxygen builds up in the oceans - oxygen builds up in the atmosphere

Question 31

What is the test for oxygen

Answer 31

- a glowing wooden splint relights in oxygen

Question 32

what is a green house gas

Answer 32

- gases found in the atmosphere which absorbs heat radiated from the earth

Question 33

Explain the green house effect

Answer 33

- electromagnetic radiation from at most wavelengths from the sun passes through the earths atmosphere - earth absorbs the necessary amount of heat needed for life on earth - but some heat is radiated from the earth as infrared radiation - some of this Infrared radiation is absorbed by green house gases in the atmosphere - atmosphere warms up leading to the green house effect and global warming

Question 34

evaluate the evidence for human activity causing climate change: - the change in atmospheric carbon dioxide concentration, the consumption of fossil fuels and temperature change

Answer 34

- increased burning and use of fossil fuels, increases the release of co2 emission - co2 adds to the greenhouse gases in the atmosphere - this will help trap more heat due to more co2, which increase the temperature from trapping more infrared rays

Question 35

Evaluate the evidence for human activity causing climate change: the uncertainties caused by the location where these measurements are taken and historical accuracy

Answer 35

the oldest temperature recorded was in central England in 1659 - however cannot be used to show global temperature as it is from one place - earlier measurements were less historically accurate as they are more prone to error and has less resolution

Question 36

Describe the composition of today’s atmosphere

Answer 36

21% oxygen 78% nitrogen 1% the rest - argon, co2, methane

Question 37

where is methane released and its dangers

Answer 37

- powerful greenhouse gas and is better at absorbing infrared rays than co2 - methane is released into the atmosphere when oil and natural gas are extracted from the found and processed - livestock farming produces a lot of methane, as cattle have bacteria in there stomach which can produce methane when they fart - soil bacteria in landfill sites also produce lots of methane

Question 38

where is co2 released

Answer 38

- released from burning fossil fuels

Question 39

What are some human effects of global warming

Answer 39

- driving - consumption of electricity and fuels - raising livestock - decay of organic waste in landfill sites

Question 40

How to limit the effects of climate change

Answer 40

- renewable energy resources can reduce gas emission - reflect sunlight back into space or capture co2 and bury it however this is a large scale engineering system which would destroy ecosystems and needs countries to work together