Chapter 16: Thermodynamics Flashcards
spontaneous process
occurs by itself without continuing external influence under certain conditions
nonspontaneous in the other direction
nonspontaneous process
will not occur unless it is driven by the continual input of energy from an external source
spontaneous in the other direction
energy dispersal
uniform dispersal of energy
transfer of heat from hot to cold
no net gain or loss - evenly dispersal drives process
matter dispersal
dispersal occurs spontaneously due to dispersal of matter
matter becomes more widely and uniformly distributed
change in internal energy is 0
allotrope
different structural forms of the same element
diamond
conversion to graphite is spontaneous but extremely slow
sp3 tetrahedral
rings of carbon
graphite
sp2, planar
sheets of linearly connection carbon
First Law of Thermodynamics
law of conservation of energy
ΔU = q + w
entropy
ΔS = q(rev)/ΔT
measure of disorder in a system
state function
reversible processes
direction can be changed by changing conditons
microstates
specific configurations of all the locations and energies of the atoms or molecules that compose a system
the distributions in which there are approximately equal number of particles in each state are most probable
S = klnW
ΔS = kln(Wf/Wi)
activation energy
kinetic quantity
enthalpy
thermodynamic quantity
related to the equilibrium constant
pressure-volume work
W = -PΔV
if W is +, then work is done on the system and it is endothermic
if work is -, then work is done by the system and it is exothermic
Second Law of Thermodynamics
spontaneous changes cause an increase in the entropy of a universe
Suniv>0 = spontaneous
Suniv<0 = nonspontaneous
Suniv=0 equilibrium
Third Law of Thermodynamics
the entropy of a pure, perfect crystalline substance at 0K is zeri
standard entropies
entropy value for the standard state of a substance
pure substance, 1 atm, 1M, 25˚C
entropy increases with
disorder or matter dispersal
increase in temperature (due to a higher kinetic energy)
standard entropies change
entropy of products - entropy of reactants
Gibbs free energy
energy available to do useful work
state function
free energy change
free energy change for a process taking place with reactants present under nonstandard conditions related to the standard free energy change
standard free energy change
change in free energy of a reaction under standard conditions
standard free energy of formation
free energy of the products - free energy of the reactants
endothermic
surroundings cooler, system warming
absorbs heat
final temperature decreases
