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23 Cards in this Set
- Front
- Back
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Thermodynamics |
The study of energy and its transformations |
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Thermochemistry |
The branch of thermodynamics that deals with heat in chemical and physical change |
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System |
The part of the universe that we are focusing |
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Surroundings |
Everything excluding the system |
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Heat |
Thermal energy, energy transferred as a result of a difference in temperature between the system and the surroundings |
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1st law of thermodynamics, Law of conservation of energy |
The total energy of the universe is constant |
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joule (J) |
The SI unit of energy |
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calorie |
Originally, the quantity of energy needed to raise the temperature of 1g of water by 1'C (specifically from 14.5'C to 15.5'C), now defined in terms of the joule |
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State function |
A property dependent only on the current state of the system (its composition, volume, pressure, temperature), not on the path the system takes to reach that state |
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Pressure-volume work (PV work) |
The mechanical work done when the volume of the system changes in the presence of an external pressure |
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Enthalpy (H) |
The internal energy plus the product of the pressure and volume H = E + PV |
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Change in enthalpy |
The internal energy plus the product of the pressure, which is constant, and the change in volume |
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Exothermic process |
Releases heat |
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Endothermic process |
Absorbs heat |
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Enthalpy diagram |
Visual depiction of enthaply changes |
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Heat capacity |
The quantity of heat required to change the temperature of a substance by 1K |
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Specific heat capacity (c) |
The quantity of heat required to change the temperature of 1g of a substance by 1K |
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Calorimeter |
A device used to measure the heat released (or absorbed) by a physical or chemical process |
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Hess's law |
The enthaply change of an overall process is the sum of the enthalpy changes of its individual steps |
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Standard states |
Gas: 1atm and ideal behavior Substance in aqueous solution: 1M concentration Pure substance: most stable form at 1atm and temperature (usually 25'C) |
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Standard enthalpy of reaction |
When the enthalpy change of a reaction is measured at the standard state |
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Formation equation |
When 1mol of a compound forms from its elements |
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Standard enthalpy of formation |
The enthalpy change for the formation equation when all the substances are in their standard states |
