energy in society

• what are the types of energy sources?

  Renewable and non-renewable.
• what are the types of renewable energy sources?

  biodiesel + bioethanol + biogas

  *bio hints that it is renewable
• what are the types of non-renewable (fossil fuels) energy sources?

  Coal, crude oil, natural gas
• how are fossil fuels formed?

  fossil fuels are formed when ancient plants, animals and microorganisms are buried under lots of earth (mud, sand, rock etc.); resulting in a lot of pressure to be applied. Thus, complex changes result in the production of the fossil fuel we know today.
• what is the chemical composition of fossil fuels?

  CHONPS

  *CHO = main elements (carbon + hydrogen + oxygen)

  *NPS = minor elements (nitrogen + phosphorus + sulfur)
• what is the definition of a non-renewable energy source?


  rate of consumption > rate of production
• what is coal?

  • coal is predominantly made from carbon
  • there are 3 types of coal:

  -black coal (low water content, high carbon content)

  -brown coal (medium water content, medium carbon content)

  -peat coal [found in bogs and lakes] (high water content, low carbon content)

  • combustion equation: C(s) + O2 (g) -> CO2(g)
  • use: electricity
  • method of extraction: mining
  • location/source: coal mines
• what is crude oil?

  • non-renewable energy source
  • mix of hydrocrabons in the form CxHy
  • alkanes are common - can range from 1 to 70 carbons
  • states:

  gas = C1 - C4

  liquid = C4 - C20

  solid = C20+

  • combustion equation: CxHy + O2 (g) -> CO2 (g) + H2O (l)
  • use:

  1. cooking
  2. fuel for transportation (octane = petrol)
  3. asphalt (road)

  • method of extraction: fractional distillation
  • location/source: under oceans
• what is natural gas?

  • non-renewable energy source
  • C1 - C4 (alkane)
  • combustion equation: CxHy + O2 (g) -> CO2 (g) + H2O (l)
  • use:

  1. cooking
  2. transportation (petrol = octane)
  3. asphalt (road)

  • method of extraction: fracking
  • location/source: shale (rock)
• what are dispersion forces?

  • attraction due to electron movement
  • it is an instantaneous dipole, hence it is weak
• what are dipole-dipole attractions?

  • attraction due to the difference in electronegativity between two elements
  • since it is permanent it is strong
• what is hydrogen bonding?

  • same as dipole-dipole but only exist in FON (this is because they have high electronegativities)
  • to create hydrogen bonds it must satisfy both inter and intramoleular bonding
  • e.g. CH4 cannot bond with HF as CH4 does not contain hydrogen bonding
• what are ion-dipole bonds?

  the attraction between an ion and a polar molecule
• what is fractional distillation?

  • Separation of a mixture into its components based on their different boiling points.
  • shorter carbon alkanes can be separated by heating the crude oil up in a furnace as different amounts of dispersion forcoes result in different boiling points - longer chain = stronger bond
• what is fracking?

  • used to extract natural gas (found in shale deposits)
  • water (hot) and other chemicals are poured into wells which cracks open shale deposits, thereby releasing the gas out (gas rises as it is hot)
• what is the law of conservation of energy?

  Energy cannot be created or destroyed, only transferred or transformed from one form to another.
• how is energy converted in a fossil fuel power plant?

  • coal as chemical energy is heated in a boiler and converted into heat/thermal energy
  • then the steam converts into kinetic energy and afterwards mechanical energy with the movement of the turbines
  • in the generator they become electrical energy
  • chem -> heat -> kinetic -> mech. -> elec.
• are fossil fuels or batteries more efficient?

  • batteries are more efficient as it is a redox reaction where energy is only converted from chemical to electrical energy
  • on the other hand, fossil fuels have to go through a lot of energy conversions and with each energy conversion, it is also converted into an undesirable form, thereby making it inefficient
• what are the advantages of fossil fuels?

  1. high energy content
  2. creates more jobs - mining
  3. contributes to the economy - exports
• what are the disadvantages of fossil fuels?

  1. non-renewable
  2. carbon emissions
• what are the advantages of biofuels?

  1. renewable
  2. theoretically carbon neutral (no net carbon release)
• what are the disadvantages of biofuels?

  1. requires land - deforestation/habitat destruction
  2. skew food supplies
• what is the definition of a biofuel?

  rate of consumption < or = to rate of production

  • replenished via natural processes within a relatively short time
• why are biofuels the way of the future?

  • becoming increasingly popular because they are renewable
  • they are not considered to contribute to an increase in atmospheric carbon dioxide
  • this is because the production of biofuels (plants) actually removes carbon dioxide from the atmosphere through photosynthesis
• what is photosynthesis?


  the process by which plants use sunlight, water, and carbon dioxide to create oxygen and energy in the form of sugar (glucose).
• what are the sources of biofuels?

  1. plants - corn/maize; sugarcane
  2. compost
• what is the chemical equation for the production of glucose for biofuels (photosynthesis) and fuel sources for the body?

  6H2O (l) + 6CO2 (g) -> C6H12O6 (aq) [glucose] + 6O2 (g)
• what is the chemical equation for the use of glucose in the human body (cellular respiration)?

  • it is a combustion/redox reaction
  • C6H12O6 (aq) + 6O2 (g) -> 6H2O (l) + 6CO2 (g)
• what is bioethanol?

  • renewable energy source
  • common use of bioethanol:
  • bioethanol is typically mixed with petrol (octane) to reduce carbon emissions - commonly known as E10/E85 (numbers represent percentage of ethanol)
  • method of production: fermentation
  • it is an anaerobic process - takes place in the absence of oxygen
• what is biogas?

  • renewable energy source
  • primarily composed of methane (main) and CO2
  • method of production: anaerobic digestion
  • it is an anaerobic process
  • bacteria consumes waste -> causes the waste to decompose and produce biogas -> the clean methane gas then rises and flows into a methane storage tank
• what is biodiesel?

  • method of production: transesterification (relocating ester group)
  • esters are formed from a condensation reaction betwen two compounds:
  • carboxylic acid + alcohol (hydroxyl group) -> H2O + ester
  • easy way to remember is carboxylic acid structural formula looks similar to ester
  • ultimately the reaction is: triglyceride (fat) + methanol -> 3 methyl esters + glycerol
• what are the four main steps of bioethanol production?(explain in detail what they involve)

  • sourcing -> pre-treatment -> fermentation -> distillation
• what does sourcing involve in bioethanol production?

  • sources of bioethanol include:
  • corn
  • sugarcane
  • mulberry
  • grapes
  • dates
  • potato
  • orange peels
• what does pre-treatment involve in bioethanol production?

  • biomass is typically comprised of cellulose which is a polysaccharide of glucose (saccharide = carbs, poly = many)
  • pre-treatment involves using sulfuric acid (H2SO4) to break down the cellulose, y thereby making it more accessiby for enzymatic hydrolysis (breaks it down)
  • once broken down, the resulting sugars can then be used in the next stage of fermentation - this helps to improve the efficiency of the overall fermentation process
• what does fermentation involve in bioethanol production?

  • now that we've attained glucose, it can then be subjected to undergo fermentation by microorganisms (such as yeast) - however must be performed in anaerobic conditions (no oxygen)
  • fermentation chemical reaction is: C6H12O6 (aq) -> (yeast) 2CO2 (g) + 2C2H6O (aq)
  • sodium hydroxide might be added during the fermentation process as it helps to neutralize the acid to prevent the denaturing of enzymes (acids denature proteins - enzymes)
• what does distillation involve in bioethanol production?

  • the fermentation broth from the fermentation stage includes both bioethanol and water
  • water is essential in the fermentation process because it helps the yeast to stay alive
  • distillation involves separating the bioethanol from water
  • this is performed in a distillation column where it is heated - exploits the difference between the two boiling points