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51 Cards in this Set
- Front
- Back
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What is a burn?
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a transfer of energy from a hot object to the human body
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The hotter an object is...
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the faster its molecules move
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Atoms and molecules are in...
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constant motion
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What is heat?
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flow of energy due to a temperature difference
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The use of energy is called...
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work
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The average US citizen enjoys the energy output from how many people?
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120
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What is thermodynamics?
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the study of energy and its transformation from one form to another
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What is energy?
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the capacity to do work
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What is work?
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a force acting over a distance
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What is an objects total energy?
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sum of kinetic and potential energy
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Thermal energy is specifically associated with the...
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temperature of an object
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What is the system?
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the subject we are thermodynamically studying
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What are surroundings?
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the environment in which the system is exchanging energy
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What is the first law of thermodynamics?
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energy can neither be created nor destroyed, only transferred between the system and the surroundings
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What is one exception to the first law of thermodynamics? Why?
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an exception occurs in nuclear processes where mass and energy are interchangeable as E=mc2
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What is the second law of thermodynamics?
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energy is dispersed (becomes arranged in a more disorderly way) in any spontaneous process
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For any spontaneous process, the entropy of the universe...
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must increase
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According to the second law of thermodynamics, no spontaneous process...
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can be 100% efficient with respect to energy
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Explain the concept of "nature's heat tax."
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an unavoidable cut of every energy transaction, additional energies is lost to its surroundings as well due to inefficiency
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Because of nature's heat tax, what are we trying to minimize?
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the amount of energy conversions it takes to reach a goal
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Explain the historical significance of the Joule.
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James Joule demonstrated that energy could be converted from one form to another, as long as total energy was conserved
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What is a Calories (cal)?
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the amount of energy required to heat 1g of water by 1 degree Celsius
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What is power?
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energy per unit time, the rate of energy input or output
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What is the basic unit for power?
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the Watt (W)= 1J/s
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What is temperature?
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the measure of the kinetic energy associated with the motion of its composite atoms and molecules
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Temperature has to do mainly with what type of energy?
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kinetic
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What is heat capacity?
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the quantity of heat energy required to change the temperature of a given amount of a substance by 1 degree celsius
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If a substance has a higher heat capacity it...
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resists changes in temperature more than other substances
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How does heat capacity effect the globe?
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the heat capacity of water affects global temperatures
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Exothermic reactions vs. endothermic reactions
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exo- gives off energy
endo- absorbs energy |
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What is enthalpy?
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the amount of heat absorbed or emitted by a chemical reaction
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What is the symbol for enthalpy?
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deltaH (lower case) rxn
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Enthalpy change refers to the point of view of...
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the syste,
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Negative enthalpy values=
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exothermic reaction
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positive enthalpy values=
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endothermic reaction
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Explain the history of American energy starting in the 1970s.
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pre 1970s- energy taken for granted
1970- North American energy crisis 1981- gas prices at historical high 1990s- big increase in energy costs post 1990s- prudency gained from the last energy crisis is largely forgotten |
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Natural gas is a mixture of...
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methane and ethane
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What is petroleum's hydrocarbon range?
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5-18+
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What is coal's hydrocarbon range?
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200+ in chains and rings
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Fossil fuels, an example of an...
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endothermic reaction
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How did ancient plants use the suns energy?
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to synthesize energetic molecules
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Photosynthesis yields...
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glucose
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What is the opposite of photosynthesis?
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combustion (releases energy)
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How much of US electricity is generated by burning fossil fuels?
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70%
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Explain smog.
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hyrocarbon combustion should only produce carbon dioxide and water, but impurities in fuels and combustion inefficiencies produce other products
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How is carbon monoxide harmful to one's body?
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it binds with hemoglobin in blood which limits oxygen transport
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What gas gives smog its brown color?
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NO2
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Smog- what does PAN do?
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stings eyes, damages rubber and crops, makes breathing difficult
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What does a catalytic converter do?
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basically makes the exhaust less environmentally harmful
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The air used in fossil fuel combustion is mostly...
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nitrogen
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Metallic oxides in water yields...
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bases
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