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IB Chemistry > Energy Option > Flashcards

Energy Option Flashcards

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1
Q

energy from the sun

A

comes from uncontrolled nuclear fusion reactions

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2
Q

photosynthesis

A
  • reaction of carbon dioxide and water to form carbohydrates in the presence of chlorophyll
  • endothermic
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3
Q

give details of photosynthesis

A
  • green pigment chlorophyll contains an extended system of alternating single and multiple bonds (conjugation)
  • substances like chlorophyll contain extended conjugation and are able to absorb visible light by exciting an electron within this conjugated system
  • energy which is absorbed by chlorophyll when it interacts with light is able to drive photosynthesis
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4
Q

how can the energy stored in biomass by released?

A
  • direct combustion of plant material
  • biogas: anaerobic decay of organic matter by bacteria produces a mixture of methane and carbon dioxide
  • fermentation to produce ethanol: carbohydrates can be fermented by enzymes in yeast
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5
Q

biofuel advantages

A
  • renewable
  • readily available
  • relatively non-polluting
  • reduces amount of waste in landfill sites
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6
Q

biofuel disadvantages

A
  • widely dispersed
  • take up land where crops can be grown
  • remove nutrients from soil
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7
Q

vegetable oils

A
  • derived from glycerol and unsaturated fatty acids
  • contain considerable amount of energy
  • cannot be used in internal combustion because they are too viscous (because they have a high molar mass)
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8
Q

transesterification

A
  • vegetable oils converted into usable fuel
  • ester can react with an alcohol to be converted into a different ester in the presence of strong acid or base
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9
Q

greenhouse effect

A

warming of the Earth caused by infrared radiation emitted by the Earth’s surface which is absorbed by various gases in the Earth’s atmosphere and then partly re-radiated towards the surface

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10
Q

greenhouse gases

A
  • water vapor
  • carbon dioxide
  • methane
  • nitrous oxide
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11
Q

Why do greenhouse gases absorb infrared radiation?

A
  • resonance
  • must be a change in dipole moment as bonds in the molecule stretch and bend
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12
Q

enhanced greenhouse effect

A

greenhouse effect caused by human activities

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13
Q

energy flow diagram of greenhouse effect

A
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15
Q

what are two consequences of global warming?

A
  • changes in agriculture and biodistribution as climate changes
  • rising sea-levels due to thermal expansion and melting polar ice caps and glaciers
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16
Q

what influences the contribution a greenhouse gas makes to global warming?

A
  • concentration in atmosphere
  • ability to absorb infrared radiation
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17
Q

ways to limit human-made emissions of carbon dioxide

A
  • reducing dependency on fossil fuels
  • capturing gas chemically using sodium hydroxide or calcium oxide
  • stored in certain types of silicon-based rocks
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18
Q

why are coral reefs being destroyed?

A
  • increase in concentration carbon dioxide in atmosphere leads to increase concentration of carbon dioxide dissolved in ocean
  • ocean more acidic
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19
Q

particulate

A
  • e.g. soot and volcanic dust
  • cool the earth by scattering the shortwave radiation from the sun and reflecting it back into space
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20
Q

energy

A

ability to do work

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21
Q

first law of thermodynamics

A

energy within a closed system can neither be created nor destroyed

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22
Q

order for the main energy sources in terms of producing energy

A

crude oil > coal > natural gas > hydroelectric > nuclear fission > wind > biofuels > solar > geothermal

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23
Q

why is the production of energy not 100% efficient?

A

heat loss

  1. to surroundings
  2. by power lines
24
Q

energy density equation

A

energy released from fuel / volume of fuel consumed

25
Q

specific energy equation

A

energy released from fuel / mass of fuel consumed

26
Q

efficiency of an energy transfer

A

useful output energy / total input energy *100

27
Q

why must sulfur be removed from crude oil before it is refined?

A

can poison catalysts by blocking their active sites

28
Q

fractional distillation

A

separating crude oil into different boiling fraction

29
Q

fraction from distillation

A
  1. refinery gas: used as fuel on site, gaseous cooking fuel, feedstock for chemicals
  2. gasoline and naphtha: cars, feedstock for organic chemicals
  3. kerosene: fuel for jet engines, domestic heating, cracked to provide petrol
  4. gas oil: diesel engines and industrial heating, cracked to provide petrol
  5. residue: fuel for large furnaces, vacuum distilled to make lubricants, bitumen used to surface roads
30
Q

cracking

A
  • process conducted at high temperatures whereby large hydrocarbons are broken down into smaller more useful molecules
  • usually alkanes and alkenes
31
Q

isomerization

A

more useful branched alkanes can be obtained from straight-chain hydrocarbons by mixing them with hydrogen and heating them at 770K over a platinum catalyst at high pressure

32
Q

what are other reforming processes?

A
  • cyclization to make ring molecules
  • aromatization to make benzene
33
Q

carbon footprint

A
  • total amount of greenhouse gases produced during human activities
  • expressed in equivalent tons of carbon dioxide
34
Q

where does the majority of the carbon footprint come from?

A

indirectly from fuel used to produce and transport goods compared with the emissions which come directly from using gasoline in their own car

35
Q

how can consumers offset their carbon footprint?

A
  • planting trees
  • reduce the use of fossil fuels and materials in general
  • reuse materials and recycle
36
Q

knocking

A

under the conditions of high temperature and pressure the reaction may start before the spark and the engine will be less efficient

37
Q

octane number

A

more branched the alkane the higher the octane number

38
Q

coal gasification

A
  • crushed coal is mixed with superheated steam
  • synthesis gas produced: mixture of carbon monoxide and hydrogen
39
Q

how to produce SNG?

A
  • reacting coal gas with more hydrogen in the presence of a heated catalyst
  • heating crushed coal in steam at 700C using potassium hydroxide as a catalyst
40
Q

SNG

A
  • cleaner gas as it removes pollution due to sulfur dioxide
  • easier to transport
  • less efficient
41
Q

Fischer-Tropsch process

A
  • synthesis gas is reacted with more steam to increase the proportional of hydrogen in the mixture
  • hydrogen and carbon monoxide are then passed into a fluidized bed reactor containing iron or cobalt catalysts to produce a mixture of hydrocarbons that can be separated by fractional distillation
42
Q

what is the primary component of natural gas?

A

methane

43
Q

coal advatnages

A
  • present in large quantities and distributed throughout the world
  • can be converted into synthetic liquid fuels and gases
  • feedstock for organic chemicals
  • has the potential to yield vast quantities of energy compared with renewable sources
  • safer than nuclear power
  • longer lifespan compared with oil or gas
44
Q

coal disadvantages

A
  • contributes to acid rain and global warming
  • not so readily transported
  • coal waste lead to ground acidity and visual and chemical pollution
  • mining is dangerous
  • dirty (produces dust, smoke and particulates)
45
Q

oil advantages

A
  • easily transported in pipelines
  • convenient fuel for use in cars
  • feedstock for organic chemicals
46
Q

oil disadvantages

A
  • contributes to acid rain and global warming
  • limited lifespan and uneven distribution worldwide
  • risk of pollution associated with transportation by tankers
47
Q

natural gas advantages

A
  • clean fuel
  • easily transported in pipelines and pressurised containers
  • does not contribute to acid rain
  • releases a higher quantity of energy per kg than coal or oil
48
Q

natural gas disadvantages

A
  • contributes to global warming
  • limited lifespan and uneven distribution worldwide
  • greater risk of explosions due to leaks
49
Q

chemical reaction vs. nuclear reaction

A
  • chemical reaction: valence shell electrons rearranged
  • nuclear reaction: nucleus itself rearranges
50
Q

nuclear fusion

A

small atoms combine to form heavier nuclei

51
Q

nuclear fission

A

splitting of heavy nuclei to form two or more lighter nuclei

52
Q

nuclear safety concerns

A
  1. meltdown: occurs when a nuclear reactor becomes out of control and essentially becomes a nuclear bomb
  2. escape of radioactive material: occur as the fuel is being transported or while it is being used
  3. high-level nuclear waste: must be stored for a very long time
  4. low-level nuclear waste: gloves, etc. that have been used in areas where radioactive materials are handled
53
Q

half-life

A

time after which the number of radioactive nuclei is reduced by a factor of 2

54
Q

how can supplies of methane be increased?

A
  • cracking larger hydrocarbons
  • coal gasification

IB Chemistry (25 decks)

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