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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. |