fuels - textbook(1.1)

Question 1

fuel

Answer 1

a fuel is a substance with stored energy that can be released relatively easily for use as heat or power. Chemical energy into electrical or thermal energy.

Question 2

non renewable resources define

Answer 2

non renewable resources are those that are used faster than they can be replaced. they are limited and eventually can be exhausted
e.g. coal, oil and natural gas

Question 3

formation of fossil fuels

Answer 3

• fossil fuels (coal, natural gas, oil) were formed from ancient plants, animals and micro-organisms that were buried under mud, sand and rock.
  -it occurs over millions of years and they cannot be replaced in the foreseeable future as a result
• the organic matter still contains some chemical energy that is originally accumulated by carrying out photosynthesis.
• chemical energy in fossil fuels can be consider trapped solar energy

Question 4

coal

Answer 4

• as wood is converted into coal, the carbon content increases and hydrogen and oxygen decreases
• the changes go from peat, brown coal then to black coal
  -black coal is a better fuel the brow coal or peat as it has higher heat value
• coal contains a mixture of carbon, hydrogen, nitrogen, sulfur and other elements

Question 5

why is black coal a better fuel

Answer 5

• as coal progresses, the amount of water decreases. so when coal is burnt the energy releases causes the water to vapourised which reduces the net amount of heat released. Because black coal contains the least amount of water, energy is not wasted on vaporising water and therefore contains the highest percentage of carbon.

Question 6

crude oil

Answer 6

• crude oil is mixture of hydrocarbon molecules, mostly from homologous series of alkanes. contains many useful compounds
• crude oil is seperated via fractional distillation- does not produce pure substances, each fraction is still a micture of hydrocarbons compounds
• these fractions can be used as fuels or treated further through chemical processes

Question 7

fraction distiallation

Answer 7

• fractional distillation uses heat to separate mixture into a number of different fractions
• the temperature of the tower decreases gradually with increasing height.
• fractions collected from trays in higher in the tower will have lower boiling points
• the boiling points of a molecular compound depends on the strength of its intermolecular forces.
• increasing molecular mass have stronger dispersion forces of its a non polar alkane molecular
• lighter alkanes condense near the top whereas heavier alkanes condense near the bottom

Question 8

natural gas

Answer 8

• fossil fuel that is mainly composed of methane and small amounts of other hydrocarbons, Water, carbon dioxide and nitrogen may be present as well
• natural gas is accessed by drilling , drilling causes the natural gas to flow to the surface. process known as fracking

Question 9

where can natural gas be found

Answer 9

• in gas reservoirs, trapped between layers of rock
• component of petroleum deposits
• in coal deposits where it is bonded to the surface on coal. Coal seams usually contain water and the pressure of the water allows the gas to adsorb to the coals surface. known as coal seam gas(CSG)
• trapped in shale rock. known as shale gas

Question 10

fracking

Answer 10

• fracking can be used to extract natural gas from coal or shale deposits
• under the pressure, the natural gas is adsorbed on the surface of coal or shale
• fracking is used to fracture the rock or coal to release the natural gas
• it begins with drilling a well into the deposit to access the trapped gas
• fracking fluid( sand, water, other chemicals) is pumped down at extremely high pressures which causes surrounding roack or coal to fracture creating fissures(cracks).
• of which the gas can flow these fissures

Question 11

cons of fracking

Answer 11

• however, fracking fluid can often impact local environment and underground water supplies
• water needs to be transported which has significant economical and environmental costs

Question 12

liquefied petroleum gas (LPG)

Answer 12

• Liquefies petroleum gas is propane and butane gas that is separated from natural gas by fractional distillation and become liquid under pressure. used for fuel and home gas bottle
• the remaining natural gas after the removal is used widely as a fuel for home heating and cooking

Question 13

renewable

Answer 13

renewable energy is energy that can be obtained from natural resources that can be constantly replenished.

Question 14

biofuels

Answer 14

• biofuels are fuels derived from plant materials such as grains, sugar cane and vegetable waste and oil.
  -main 3 types are biogas bioethanol and biodiesel
• they can be used alone or blended with fossil fuels(petrol and diesel
  -less impact on environment than fossil fuels as plant amterial are produced by photosynthesis which removes co2 from the atmosphere and produces glucose

Question 15

photosynthesis equation

Answer 15

6CO2 + 6H2O —> C6H12O6 + 6O2
carbon dioxide + water —> glucose + oxygen

Question 16

bio ethanol

Answer 16

• enzymes in yeast help to convert it into starches
• it then catalyses the breakdown of the starch into glucose in which the enzymes convert glucose into ethanol and carbon dioxide
• this is down through the process of fermentation
• can be used for cars

Question 17

fermentation of yeast

Answer 17

C6H12O6 —> 2CH3CH2OH + 2CO2
glucose ——-> ethanol + carbon dioxide

Question 18

bio gas

Answer 18

• gas that is released in the breakdown of organic waste by anaerobic bacteria (rotting rubbish, decomposing plant material)
• these bacteria decompose the complex molecules(carbohydrates and proteins) into simple molecular compounds (carbon dioxide and methane)
  -mainly contains of methane and carbon dioxide
• can be used for heating and to power homes and farms
• doesn’t have high energy content as it doesnt contain as much methane than fossil fuels

Question 19

bio diesel

Answer 19

• bio diesel is a mixture of organic compounds known as esters
• these esters are produced by a chemical reaction between vegetable oils or animal fats and an alcohol(methane usually)

Question 20

carbon neutral

Answer 20

Carbon neutral means that carbon absorbed/removed in production of the fuel equals
carbon released by combustion.