Unit 7: Energy
Jan. 2016
10.1
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Energy: The capacity to do work
o Potential Energy (PE) : resting/ stored energy
o Kinetic Energy (KE) : Energy of motion KE = mv2
Law of conservation of energy: Energy cannot be created nor destroyed only converted into different
forms.
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Temperature: Average Kinetic energy.
Heat (Q): The flow of thermal energy between two objects when there is a difference in
temperature.
o Flows from hot to cold, more energy to less energy
State Function: the end result is INDEPENDENT of the path taken
System: What is being studied by the observer
Surroundings: Everything else
Endothermic: When energy flows into the system
o Q > 0 (greater than zero)
Exothermic: Energy flowing out of the system
o Q < 0 (less than zero)
10.2
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Units for heat:
o Joules (J) – SI unit for energy
o Calories (cal) : the amount of energy requires to raise ONE GRAM ONE degree Celsius
o BTU: British Thermal Units
1 calories = 4.184 Joules
Specific Heat Capacity: the amount of energy requires to raise ONE GRAM of a substance ONE
degree Celsius
o For water it is 4.184 J/ g C or 1.0 cal/ g C
o Specific to each substance
o Used to determined what the substance can be used for
o Q= (Cp)(m)(ΔT)
 Q= heat
 Cp = specific heat capacity
 Can also be indicated as S
 m = mass (in grams)
 ΔT = TF - TI
 Change in temperature