powerpoint Flashcards
spontaneous process
a process that occurs without outside intervation
nonspontaneous process
a process that only occurs as long as energy is continually added to the system
spontaneity depends on…
dispersion of energy
many spontaneous processes are…
exothermic
entropy
measure of how dispersed the energy in a system is at a specific temperature
energy distribution is affected by…
molecular motion and volume
second law of thermodynamics
the total entropy of the universe increases in any spontaneous process
for a system to be spontaneous, deltaSuniv…
must be greater than 0
if Ssys is less than 0…
Ssurr must be greater for Suniv to be greater than 0
if Suniv is not greater than 0…
the process is not spontaneous
reversible process
process that can be run in the reverse direction, the system has been restored to its original state, no net energy has flowed either to the system or its surroundings
if Ssys and Ssurr are greater than 0…
always spontaneous
if Ssys is less than 0 and Ssurr is greater than 0
spontaneous if Ssys is less than Ssurr
nonspontaneous if Ssys is greater than Ssurr
if Ssys is greater than 0 and Ssurr is less than 0
spontaneous if Ssys is greater than Ssurr
nonspontaneous if Ssys is less than Ssurr
if Ssys and Ssurr are less than 0…
always nonspontaneous
third law of thermodynamics
the entropy of a perfect crystal is zero at absolute zero
standard molar entropy
the absolute entropy of one mole of a substance in its standard state at 298 K and one bar of pressure
as the complexity of molecular structure increases,
entropy increases
qsurr =
-deltaHsys
gibbs free energy
the maximum energy released by a process occurring at constant temperature and pressure that is available to do useful work
if the system experiences an increase in entropy then,
Srxn is greater than 0
if the process is exothermic
Hrxn is less than 0
deltaGf
the change in free energy associated with the formation of one mole of it in its standard state from its elements in their standard states
deltaG =
energy that does work
if H is negative and S is positive
deltaG is always less than 0 and always spontaneous
if H and S are negative
deltaG is less than 0 at lower temperatures and spontaneous at lower temperatures
if H and S are positive
deltaG is less than 0 at higher temperatures and spontaneous at higher temperatures
if H is positive and S is negative
deltaG is greater than 0 and never spontaneous
deltaG is less than 0, K is
large and favors the products
deltaG is slightly negative, K
slightly favors the products
deltaG is greater than 0, K is
small and favors the reactants
