Ch 7: Thermochemistry Flashcards
isolated system
exchange neither matter nor energy with the environment
closed system
exchange energy but not matter with the environment
open system
exchange both energy and matter with the environment
isothermal
processes occur at a constant temperature
adiabatic
processes exchange no heat with the environment
isobaric
processes occur at a constant rate
isovolumetric (isochoric)
processes occur at a constant volume
state functions
describe physical properties of an equilibrium state; pathway independent
pressure, density, temp, volume, enthalpy, internal energy, gibbs free energy, entropy
under PRESSURE feeling DENSE, i want HUGS and TV
standard conditions
298K
1 atm
1 M conc
standard state of an element is prevalent under standard conditions
stand enthalpy, stand entropy, stand free energy
phase changes exist at
characteristic pressure and temperatures
fusion is ___ and freezing is ___ occur btw solid and liquid phases
melting
crystallization or solidification
vaporization _____ and condensation occur btw liq and gas
evaporation or boiling
occur at boundary btw solid and gas phase
sublimation and deposition
at temps above the _____ liq and gas phases are indistinguishable
critical point
at the ____ all 3 phases of matter exist in equilibrium
triple point
temperature
scaled measure of average kinetic energy of a substance
heat
transfer of energy that results from difference of temperature between two substances
enthalpy
measure of the potential energy of a system found in intermolecular attractions and chemical bonds
hess’s law
states that the total change in potential energy of a system is equal to the changes of potential energies of the individual steps of the process
can be calculated using heat of formation, heats of combustion, or bond dissociation energies
enthalpy
entropy
often thought of as disorder, measure of degree to which energy has been spread throughout a system or between a system and its surroundings
ratio of heat transferred per mole per unit kelvin
maximized at equilibrium
gibbs free energy
derived from both enthalpy and entropy and determines if process is spontaneous or non-spontaneous
depends on temperature; temp dep processes change btw spontaneous and nonspontaneous depending on the temp
