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P Chem
| Term | Definition |
|---|---|
| thermodynamics | study of transformation of energy |
| system | the quantity of matter when we can draw a boundary |
| surroundings | region outside system we make measurements |
| open system | matter and energy CAN be transferred through boundry between system and surroundings |
| closed system | matter CANNOT be transferred through boundry. Energy CAN be transferred. |
| isolated system | closed system that has no mechanical/thermal contact with surroundings CANNOT transfer matter or energy |
| work | done to achieve motion against an opposing force:Raise weight. when a force acts upon an object to cause displacement of an object. eg. Pushing shoprite cart. |
| energy | capacity to do work |
| heat | energy transferred due to temp. differences ONLY |
| diathermic | boundries that DO permit transfer of energy as heat |
| adiabatic | boundries that do NOT permit transfer of energy as heat |
| exothermic | releases energy as heat into suroundings. combustion increase TEMP |
| endothermic | energy is absorbed by sustem from surroundings as heat |
| thermal motion | disorderly molecular motion in surroundings. |
| internal energy | total energy of system state function deyltaU |
| state function | value depends only on current state of system independent of path |
| first law of thermodynamics | internal energy of an isolated system is constant |
| expansion work | work arising from change in volume |
| nonexpansion work/ additional work | work arising from no change in volume |
| free expansion | expansion against zero opposing force |
| indicator diagram | graph used to show expansion of work |
| reversible change | change that can be reversed by an infinitesimal ,small modification of a variable. |
| calorimetry | study of heat transfer during physical and chemical process. |
| calorimeter | device used to measure energy energy transferred as heat |
| adiabatic bomb calorimeter | measures internal energy when q=0 |
| calorimeter constant | c |
| heat capacity | slope tangent to curve at any temp |
| molar heat capacity | Cvm=Cv/n |
| specific heat capacity | Cv/mass |
| enthalpy | u+pV |
| isobaric calorimieter | constant pressure |
| adiabatic flame calorimeter | constant volume |
| differential scanning calorimeter | measure H |
| thermochemistry | study of energy transferred as heat in chem rxn |
| std enthalpy | change in enthalpy when the inital and fianl substances in std state |
| std state | 1 bar |
| std enthalpy of transition | change in physical state |
| hfus | s to l |
| hvap | l to g |
| lattice enthalpy | change in std molar enthalpy |
| born haber cycle | solves for lattice enthlpy |
| thermochemical equation | combo of chem eq and corresponding change in std enthalpy |
| std reaction enthalpy | sum of H prod - Sum of Hreac |
| std enthalpy combustion | complete oxidation of organic compound to co2 gas and liquid h2o is contains CHON |
| hess law | enthalpy of an overall rxn is the sum of std enthalpies of individual rxns into which a rxn maybe divided. |
| std enthalpy of form | std rxn enthalpy for formation of compound from its elements in ref states. |
| reference state | most stable state 1 bar |
| stochimetric numbers | vj Hprod-Hreac |
| kirchoff Law | equates emission and absorption in heated objects |
| path functions | depend on path between 2 states |
| exact differential | small quanitity when integrated gives a result that is independent of path between initial and final state. |
| inexact differential | small quantity when integrated gives a result that depends on path between initial and final states. |
| internal pressure | internal energy of system changes when it expands or contracts at constant temp |
| expansion coeff | fractional change in volume when temp increases |
| isothermal compressibility | fractional change in volume when pressure increases |
| isenthalpic | constant enthalpy |
| isothermal joule thomson coeff | slope of graph p vs t |
| inversion temp | critical temp when non ideal gas is expanding at constant enthalpy temp is decreasing. |