Option C: Energy

• advantages of natural gas

  relatively clean, higher specific energy than coal and oil, can be compressed or liquefied, does not contribute to acid deposition
• disadvantages of natural gas

  non-renewable energy source, produces greenhouse gas, natural gas has lower energy density than coal and oil, unevenly distributed throughout the world
• energy density


  energy stored in a given space per unit volume
• specific energy 


  energy stored in a given space per unit mass
• advantages of coal

  relatively cheap, high specific energy density, can be liquified, distributed throughout the world
• disadvantages of coal

  non renewable energy source, produces green house gas, contains sulfur which causes acid deposition, mining coal causes environmental damage
• advantages of crude oil

  relatively cheap, high specific energies and energy densities, petroleum products are easily transported, valuable feedstock for petrochemicals
• disadvantages of crude oil

  non renewable energy source, produces greenhouse gas, drilling for oil causes environmental damage, unevenly distributed throughout the world
• fractional distillation 


  splitting petroleum into a mixture of hydrocarbons
• How does the tendency of a fuel to auto-ignite relate to the molecular structure?

  Shorter chains will have a higher octane number as they are less prone to auto-igniting

  Longer chains will have a lower octane number as they are more prone to auto-igniting
• what is cracking 


  breaking large hydrocarbons into separate smaller chains
• what is catalytic reform 


  aromaticization
• isomerization 


  creating a structural isomer with a shorter main chain
• fast breeder reactors 


  generates more fissile material than consumed
• disadvantages of nuclear fission


  radioactive waste classified as low level, intermediate level, or high level waste
• low level radioactive waste

  gloves, protective clothing, paper towels from labs or hospitals
• high level radioactive waste

  spent fuel rods are removed from the reactor core and stored in cooling ponds
• how can low level radioactive waste be disposed of

  bury in shallow repositories
• how can high level waste be disposed of

  vitrification (glass storage) and storing in geologically stable underground areas
• decay constant

  t1/2 (radioactive half life) = ln2/λ (decay constant) 
• why would an atom undergo nuclear fission

  binding energy per nucleon increases and nuclei become more stable
• what makes an isotope the most stable

  highest binding energy per nucleon
• critical mass 


  minimum mass for a substance to self propagate in a chain reaction to sustain nuclear fission
• how is light absorbed in green plants

  Pigment molecules have extensive conjugation which consists of many alternating single and double bonds. The electrons in the extensively conjugated system are delocalized and may be excited to transition to higher energy levels.
• glucose fermentation

  converts glucose into ethanol in the presence of yeast or bacteria which can be used as a biofuel
• why can't vegetable oils be used in place of diesel fuel

  vegetable oils are too viscous as a result of their higher molar masses as well as being less volatile than regular diesel
• transesterification 


  Biodiesel creation in which glycerol and alkyl esters may be produced through a reaction between a triglyceride and methanol/ethanol - the catalyst in this reaction is a strong base or strong acid. This reaction is reversible meaning an excess of alcohol is used to shift the equilibrium to the right in favors of the products
• general equation for transesterification

  RCOOR1 + R2OH → R1OH + RCOOR2
• advantages of biofuels

  high octane rating, produces less greenhouse gasses, renewable energy source
• disadvantages of biofuels

  more volatile and evaporates more easily, lower specific energy than octane, loss of biodiversity
• greenhouse effect 


  greenhouse gasses in the atmosphere are transparent and allow the passage of incoming short wavelength solar radiation to reach the surface of the Earth which redistributes radiation back into the atmosphere as longer wavelength (infrared) radiation. Greenhouse gases in the atmosphere absorb this longer wavelength radiation and redistribute it back to the surface of the Earth, causing the temperature at the surface to increase.
• greenhouse gas potency


  the greenhouse factor and the relative abundance
• vibrational modes 


  molecule vibration corresponds to the frequency of infrared radiation
• two vibrational modes 


  asymmetric stretching and bending
• how does a gas absorb infrared radiation

  change in dipole movement of the molecule as bonds undergo asymmetric stretching and bending whilst IR active
• vibrational modes that absorb IR radiation

  IR active
• IR inactive

  diatomic molecules
• effects of global warming

  rising sea levels, melting of the polar ice caps, thermal expansion of the ocean, droughts, flooding, natural disaster
• method of reducing carbon dioxide

  use renewable energy sources, reduce carbon footprint, carbon capture
• how does ocean acidification occur?

  Carbon dioxide dissolves in seawater, forming carbonic acid and lowering the pH of the ocean.

  CO2(g) ⇌ CO2(aq)

  CO2(aq) + H2O(l) ⇌ H2CO3(aq)

  H2CO3(aq) ⇌ H+(aq) + HCO3-(aq)