Download Chapter 10 Energy PowerPoint

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Energy: ability to do work
Potential energy: stored energy
Kinetic energy: energy due to motion KE = ½ mv2
Law of conservation of energy: Energy can
neither be created or destroyed.
Work: Force acting over a distance
State function: A property of a system that
changes independently of its pathway. Energy
change is a state function whereas heat and work
are not.
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Temperature: Average kinetic energy
Heat: Flow of energy due to a temperature
difference. It is the total kinetic energy.
System: Part of the universe you are observing.
Surroundings include everything else in the
universe.
Exothermic: energy flows out of the system
Endothermic: energy is absorbed from the
surroundings.
In any exothermic reaction, some of the potential
energy stored in the chemical bonds is converted
to thermal energy as heat.
Heat flow into the surroundings (exothermic)
LOWERS the potential energy.
What does an endothermic process do to the
potential energy of a system?
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Internal energy: sum of the P.E. and the K.E. of a
system. ΔE = q + w where q = heat and w = work
A calorie is the amount of energy it takes to raise 1
gram of a substance 1.0oC.
1 calorie = 4.184 J
Specific heat capacity is the amount of energy
needed to raise the temperature of 1 gram of a
substance 1 degree Celsius. S.H. for liquid water is
4.184 J/g oC.
Q = m· c· ΔT
OR
J = g · ΔT · S.H.
Enthalpy: The amount of energy that is produced
or absorbed in a given reaction. ΔH
Calorimeter: A device used to determine the heat
associated with a chemical reaction.
Hess’s Law: In going from a particular set of
reactants to a particular set of products, the
change in enthalpy is the same whether the
reaction takes place in one step or in a series of
steps.
Entropy: a measure of disorder or randomness.
ΔS
Law of Conservation of Energy: Energy can neither be created or
destroyed.
When we use energy, we degrade its usefulness and the quality of
that energy is lowered.
Concentrated energy (like gasoline) used to do work becomes energy
that is spread out throughout the universe.
Energy concerns are based on the quality, not the quantity of energy.
The concept of the “heat death” of the universe addresses the
eventuality that at some point in time all the energy will be spread
evenly throughout the universe and thus will be at the same
temperature. At this point, it would no longer to do any work and the
universe will be “dead”.
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Sources of energy in our world include:
Wood
Coal
Petroleum: made of hydrocarbons
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Gasoline, kerosene, diesel, heating oil, asphalt
Natural gas: primarily made of methane
Hydro: water
Nuclear
Solar