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25 Cards in this Set
- Front
- Back
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First Law of Thermodynamics
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energy of the universe is constant
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Second Law of Thermodynamics
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in any spontaneous process, there is always an increase in the entropy of the universe
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Third Law of Thermodynamics
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entropy of a perfect crystal @ 0 Kelvins is ZERO
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Carnot Cycle
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interconversion of heat energy & work energy
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Free Energy
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-G (favorable forward)
+G (unfavorable forward -> favorable reverse) |
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If S (+), H (-)
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favorable @ all temps
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If S (+), H (+)
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favorable @ high temps
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If S (-), H (-)
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favorable @ low temps
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If S (-), H (+)
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unfavorable @ all temps
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R =
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8.314 J/mol*K
0.0821 L*atm/mol*K |
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deltaGrxn =
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deltaG' + RTlnQrx
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deltaG =
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RTln(Qrx/Keq)
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Enthalpy (H) defined as
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the quantity of heat present in a system; the heat either lost from or added to a system
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Heat energy is needed to ____ bonds, while heat energy is released when bonds are ____.
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break; formed
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Rubber band stretched to relaxed.
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deltaG[stretched-to-recoiled] is a (-).
rubber band becomes cold when it goes from stretched to relaxed endothermic processes absorb heat and therefore feel cold -> H is (+) S (+) becomes more disordered |
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Calorimetry
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measurement of heat released from or absorbed by a chemical rxn or physical process
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heat transferred to heat sink
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if temperature decreases --> endothermic
if temperature increases --> exothermic |
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the greater the amount of energy required to increase the vibrational energy of a substance, the greater its..
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heat capacity
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The material with the greater heat capacity reaches a ___ temperature when they are both exposed to the same amount of energy.
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lower
btw phase change processes have little to do w/heat capacity |
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Convection (via fluid medium)
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heat through fluid via thermal currents
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Conduction (via direct contact)
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heat by collisions
-> heat gradients formed |
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Radiation (absorption and emission of IR photons)
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emission of photon energy in forms of EM waves
hot objects emit infrared photons |
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Evaporation-Condensation
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evaporation is an endothermic process in which a liquid absorbs heat & is converted into a gas
condensation is an exothermic process whereby heat is released from a gas as it is converted into a liquid. |
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Exhale through your mouth w/a small opening, the air feels cooler as it passes across your skin.
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That is due to the compression of the gas (exothermic) as it passes through your lips and the expansion of the gas (endothermic) once it leaves your mouth. When a gas expands, the molecules increase their intermolecular distance, which breaks intermolecular forces. Just as bond breaking is endothermic, so is the expansion of gas.
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Heat Pump
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Counterclockwise path abt the phase change process
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