Chapter 16 Key Terms - Thermodynamics Flashcards
(25 cards)
Spontaneous Process
Process that takes place without any continuous input of energy from an external source
Non spontaneous Process
A process that requires the continual input of energy from an external source
Energy Dispersal
Denoted as Entropy (S)
Favorable when a change in entropy is (+)
Driving force –> uniform dispersal of matter
hot to cold is spontaneous (loss/gain thermal energy)
No change in internal energy (q=0)
Matter Dispersal
Matter will spontaneously disperse through the dispersal of matter
Matter will become more widely distributed and more uniform
Change in internal energy is 0
Allotrope
Diamond allotrope –> graphite allotrope
Different structural forms of the same element
Diamond
The conversion to graphite is spontaneous but extremely slow due to high Ea
Rings of carbon
Sp3 tetrahedral
Graphite
SP2, planar
sheets of linearly connected carbon chain
First Law of Thermodynamics
Law of conservation of energy
Isolated system so there will be no change in the internal energy (q=0)
ΔU = q + w
Entropy
Dispersal of matter –> measures disorder in a system
Dependent on the state function:
(+) entropy is favorable
(-) entropy is unfavorable
ΔS = q(rev)/ΔT
Reversible Processes
When changing the condition, we can change the direction of the reaction
Microstates
The specific configurations and locations that al the atoms, particles, and molecules that can compose a system
S = klnW
ΔS = kln(Wf/Wi)
Wf>Wi means increase in entropy (+)
Wf < Wi means decrease in entropy (-)
Greater number of microstates means greater entropy and is most probable
–> This means that equal number of particles in each state are most probable
Second Law of Thermodynamics
Spontaneous changes can cause in increase in the entropy of a universe
ΔSuniv>0 = (+) Favorable and spontaneous
ΔSSuniv = 0 –> Equilibrium
ΔSuniv = ΔSsys + ΔSsurr
Third Law of Thermodynamics
Entropy of a pure crystallin solid is 0 at 0K
Standard Entropies
Entropy for the standard state of a substance
Pure substance, 1 atm, 1 M, 25 ˚C
Standard Entropy Change
Change in entropy for a reaction calculated using the standard entropies
entropy of products - entropy of reactants
Gibbs Free Energy Change
energy available to do useful work
state function
Thermodynamic property
(-) = Spontaneous
Free Energy Change
Thermodynamic property
free energy change for a process taking place with reactants present under NONSTANDARD conditions is related to the standard free energy change
ΔG = ΔH - TΔS
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
Exothermic
Surroundings warmer, System cooler
Releases heat
Final temperature increase
Enthalpy
the total heat content of a system
H = U + PV
Activation Energy
Kinetic Quantity
Enthalpy
Thermodynamic Quantity
Related to the equilibrium constant
