Petroleum: To build or To Burn

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Petroleum To build or To Burn

• Part 3B
• Petroleum as a Source of Energy

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Introduction

• 1. How is petroleum thought to be formed?
• plants and animals died and eventually covered
  with sediments
• pressure, heat, and microbes converted the living
  matter into petroleum trapped in porous rocks

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• Describe the history of the use of Petro?
• (2 slides)
• began to be used 5000 years ago
• ancient Middle Easterners collected the petro
  that seeped from the ground and used it to
  waterproof ships and canals, and the pave roads

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• 1000 AD, Arabs had developed a way of processing
  oil to make kerosene for lighting, at the same
  time the Chinese were extracting oil from wells
  that were half mile deep
• First oil well in the US was in PA in 1859

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Energy Past, Present, and Future

• 3. What is our main source of energy?
• the sun
• 4. How is this energy stored?
• as chemical energy in plants
• 5. How is the energy transferred?
• animals eat these plants storing the energy in
  biomolecules

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• 6. Name some examples of stored energy?
• wood, water, wind, and animal power
• 7. What used to be our main source of stored
  energy?
• Wood
• http//www.eia.doe.gov/emeu/aer/eh/frame.html
• Resource info on history of petroleum use

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• Use Figure III.10 to answer the following
  questions
• 8. Since 1850, has our overall use of energy
  remained constant, increased at a fixed rate, or
  accelerated? Describe at least two factors that
  might explain he trend.
• 9. Did overall energy use decrease at any time?
• 10. Over what time period did wood supply more
  than 50 of our overall energy needs? What was
  the chief form of long distance transportation
  during this period?

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• 11. What factors might explain the declining use
  of wood after this period? What energy was the
  next to rise in importance?
• 12. Compared to other energy sources, only a
  small quantity of petro was used prior to 1910.
  What do you think was petros main use at that
  time?
• 13. Oil became increasingly important about the
  same time that the use of coal reached its peak.
  When did this occur? What can explain the
  growing use of petro after this date?

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• 14. What is the most recent energy source to
  enter the picture? What is the major use of this
  energy source?
• 15. cut
• Do Chemquandary 1 on page 195

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Energy and Fossil Fuels

• 16. What are fossil fuels?
• petroleum, natural gas, and coal
• 17. From where do fossil fuels originate?
• biomolecules of prehistoric animal and plant life

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• 18. What is one way of thinking of the concept
  of energy being released from fossil fuels?
• energy stored in loaded mousetrap, energy must be
  put in to set it, then when it is triggered,
  energy is released
• 19. How is chemical energy released?
• during the breaking or forming of bonds during a
  chemical reaction

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• 20. Give an equation that demonstrates this
  release.
• 2H2 O2 --gt 2HOH energy
• 21. What do we call the release of energy in a
  reaction?
• exothermic reaction

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• 22. What do we call the addition of energy to
  make the reaction get started?
• activation energy
• 23. What analogy can be used to explain an
  exothermic reaction?
• kicking a stone to the top of a hill and having
  it fall down

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• 24. What kind of reaction is one that takes in
  energy?
• endothermic
• 25. What analogy can be used to explain an
  endothermic reaction?
• having to roll a big boulder up a hill

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• Draw Energy Diagrams to demonstration both endo
  and exo reactions

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Important to add to study guide

• Generally, it takes energy to BREAK bonds and
  FORMING bonds gives off energy
• All reactions have both exothermic and
  endothermic parts, but the reaction is labeled
  whichever part involves a GREATER amount of energy

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• 27. What are energy conversions?
• converting of one form of energy into another
• 28. What are some different types of energy?
• chemical, electrical, electromagnetic(light),
  heat, sound, mechanical, electrostatic, magnetic

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29. What are the energy conversions in the
following examples? a. drying your hair (see
next slide for answer) b. photosynthesis c.
gasoline to rear window defrosting in an
automobile
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• 30. What are two problems associated with energy
  conversions?
• 1. You will lose energy with every
  interconversion
• 2. Sometimes pollution is emitted with every
  interconversion
• 31. How efficient is a well tuned automobile?
  What happens to the rest of the energy?
• about 25 efficient. The rest is lost to the
  surroundings

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• 32. What would be one way of increasing the
  energy efficiency in machines?
• reduce the number of energy conversions
• Read Chem at Work on page 198 for Quiz tomorrow

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The Chemistry of Burning

• 33. What is the overall reaction that is
  involved in most examples of burning?
• Hydrocarbon O2 --gt CO2 H2O
• 34. Give the equation for the burning of a
  candle candle wax is C25H52
• C25H52 O2 --gt CO2 H2O Heat

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• Do 37-38 then come back
• 35. What is heat of combustion?
• the amount of energy given off when something is
  burned
• 36. What equation is used to determine heat of
  combustion?
• q m x T x SH
• q is the energy given off or absorbed during a
  reaction,
• m is mass of the stuff being heated
• T is the final temperature minus the initial temp
  
• SH is the Specific Heat of the substance being
  heated

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• (When using this equation, its almost always
  water that is being used to measure the energy
  change)
• 37. What is specific heat?
• the amount of energy that a 1 g sample of a
  substance can absorb before it can go up 1 C
• The unit is J/gC
• how much energy for each gram to go up 1 degree

http//www.kentchemistry.com/links/Energy/Specific
Heat.htm
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• 38. Determine whether the following materials
  would have a high or low specific heat
• Oil
• Water
• Plastic
• Wood
• Perfume
• Alcohol

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• 39. What are the heat of combustions for the
  common fuels that we use?
• Fuel name HOC in kJ/g
• CH4 methane 55.6
• C3H8 propane 50.0
• C6H14 hexane 48.2
• C7H16 heptane 48.2
• C8H18 octane 47.8
• 40. What is the heat of combustion for coal?
• 25 kJ/g

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• Ex. 1 How much energy is given off when 3.00 g
  of a candle burns to heat up 50 g of water from
  20 C to 30 C? The specific heat of water is 4.18
  J/gC. What is its heat of combustion? In kj

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• Ex. 2 How much energy is given off when 5.00 g of
  gasoline burns to heat up 50 g of water from 20 C
  to 35 C? The specific heat of water is 4.18
  J/gC. What is its heat of combustion in kj/g?

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Example 3 (like hw 22)

• 2 g methane are burned, heating 500 g of water.
  The water goes from 10 to 63 degrees C.
• a. calculate the heat produced (in Joules)
• b. calculate the heat of combustion of the fuel
  in kJ/mol

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• 41. What happened to the use of Kerosene after
  the invention of the electric light bulb?
• Drastic decline
• 42. What did chemist figure out what to do at
  this time?
• Process of converting larger moelcules in
  kerosene into smaller, gasoline sized molecules
  by heating it to 600 to 700C

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• 43. What do we call this process?
• Cracking
• 44. How much of todays crude oil is cracked?
• A third
• 45. How has the process been improved?
• By adding a catalyst

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• 46. What is a catalyst?
• A substance that increases the speed of a
  reaction without affecting it in any other way
• 47. What is an example of a catalyst that is
  used by human beings to digest foods? (mistake on
  s.g. question)
• enzymes

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• 48. Without enzymes, how long would it take for
  you to digest todays meal?
• Months
• 49. What is the most common substance produced
  from cracking?
• gasoline

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• 50. What is gasoline composed of?
• Chains of carbon, 6 carbon(hexane), 7
  carbon(heptane), and 8 carbon(octane) long
• 51. Draw the dot diagram for octane(C8H18)?

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• 52. What causes engine knocking?
• Rapid burning of the fuel
• 53. How did chemist solve this problem?
• By using branched chain molecules

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• 54. What is an isomer?
• Same formula different structure
• 55. Draw an isomer of octane

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• 56. What is an octane rating?
• Describes the quality of the fuel
• 87 Isooctane, 13 heptane is 87 octane

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• 57. What is a cheap way of increasing octane
  rating?
• Adding tetraethyl lead(C2H5)4Pb to the fuel
• 58. What did the tetraethyl lead do?
• Slowed down the burning of the straight chain
  hydrocarbons

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• 59. Why has this method been banned?
• Lead was discharged into the atmosphere along
  with the exhaust gases
• Lead is very harmful to the environment
• 60. So what have gasoline makers relied on?
• Oxygenated fuels

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• 61. What are oxygenated fuels?
• Hydrocarbons that contain oxygen like alcohols
• 62. What are the advantages to using alcohols?
• Makes the fuel burn more efficiently and cleaner
• Cheap to make

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• 63. What is a good example of these alcohols?
• Methanol
• 64. What is methanol made from?
• Natural gas, corn, coal, wood

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• 65. What other alcohol is used?
• Ethanol-drinking alcohol
• 66. What is a promising new fuel additive?
• MTHF, methyltetrahydrofuran, has an octane rating
  of 87 and the ability to increase the oxgyen
  level of the gas. Made from renewable resources
  that can be found in Paper mill waste

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• Do Chemquandary 2 on page 211
• Do Making Decisions on Page 212