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To understand how the quality of energy changes as it is used

Objectives. To understand how the quality of energy changes as it is used To consider the energy resources of our world To understand energy as a driving force for natural processes. A. Quality Versus Quantity of Energy. When we use energy to do work we degrade its usefulness.

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To understand how the quality of energy changes as it is used

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  1. Objectives • To understand how the quality of energy changes as it is used • To consider the energy resources of our world • To understand energy as a driving force for natural processes

  2. A. Quality Versus Quantity of Energy • When we use energy to do work we degrade its usefulness.

  3. A. Quality Versus Quantity of Energy • Petroleum as energy

  4. B. Energy and Our World • Fossil fuel – carbon based molecules from decomposing plants and animals • Energy source for United States

  5. B. Energy and our World Electricity Production in the US (2006)

  6. B. Energy and Our World • Petroleum – thick liquids composed of mainly hydrocarbons • Hydrocarbon – compound composed of C and H

  7. B. Energy and Our World

  8. B. Energy and Our World • Natural gas – gas composed of hydrocarbons, mainly methane (CH4)

  9. B. Energy and Our World • Coal – formed from the remains of plants under high pressure and heat over time; solid composed mainly of Carbon

  10. B. Energy and Our World Burning Fossil Fuels: Coal: C + O2 CO2 Natural Gas: CH4 + O2  CO2 + H2O Gasoline (Petroleum) : C8H18 + O2  CO2 + H2O

  11. B. Energy and Our World • Effects of carbon dioxide on climate • Greenhouse effect

  12. B. Energy and Our World • alternative energy sources • Solar • Nuclear • Biomass • Wind • Geothermal • Tidal

  13. B. Energy and Our World • Effects of carbon dioxide on climate • Atmospheric CO2 • Controlled by water cycle • Could increase temperature by 10oC

  14. C. Energy as a Driving Force • Natural processes occur in the direction that leads to an increase in the disorder of the universe. • Example: • Consider a gas trapped as shown

  15. C. Energy as a Driving Force • What happens when the valve is opened?

  16. C. Energy as a Driving Force • Two driving forces • Energy spread • Matter spread

  17. C. Energy as a Driving Force • Energy spread • In a given process concentrated energy is dispersed widely. • This happens in every exothermic process.

  18. C. Energy as a Driving Force • Matter spread • Molecules of a substance spread out to occupy a larger volume. • Processes are favored if they involve energy and matter spread.

  19. C. Energy as a Driving Force • Entropy, S – function which keeps track of the tendency for the components of the universe to become disordered

  20. C. Energy as a Driving Force • What happens to the disorder in the universe as energy and matter spread?

  21. C. Energy as a Driving Force • Second law of thermodynamics • The entropy of the universe is always increasing.

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