Thermo 3 Energy Enthalpy Entropy Flashcards
What is the equation for Enthalpy
H= E+PV
E is energy
What types of reactions does Enthalpy include
Adiabatic + isobaric reactions
What is an isobaric reaction
Constant pressure environment
Since we assume Enthalpy is at constant pressure (isobaric) and adiabatic what does the equation turn into
From H=E+PV to delta H= dQ + VdP
But since constant pressure
delta H= dQ p (p to show constant pressure)
A change in Enthalpy generally means what
A change in heat (delta Q)
Is Enthalpy temperature independent or dependent
Temp dependent
What are the laws of thermodynamics
Temperature maps thermodynamic equilibrium: If T1=T2 and T2=T3, Then T1=T3
Energy is cosereved: delta U = W+Q
Entropy increases : delta S >/_ zero (
What happens if entropy is zero
Explain the absolute zero saying
Nothing happens
By extension of the first law, to reach absolute zero you would need something colder than absolute zero to cool it to absolute zero (temp equilibrium)
What is heat death
Entropy gradually increase
So eventually the universe gains so much disorder, leading to the death of the universe
Whag is entropy
Disorder
The energy accessible to be used as work
Entropy equation
S=KB ln (ohm)
Explain the temperature increase effects on entropy from solid to liquid
First heating the solid to the melting temp increases the entropy because more vibrations of molecules in the ordered crystal array (can see some defects)
Melting the solid at Tm increase entropy by breaking up the ordered array
During this melting the T is constant but S is increasing because more defects in the crystal
During this melting the solid and liquid are in thermal equilibrium (no heat transfer between them since at same temp)
Explain the temperature increase effects on entropy from liquid to gas
Heating the liquid increases S because more vibration and rotation of molecules, random movement as the molecules roll around each other
Then evaporating that liquid at Tbp increases S because of separation of the atoms in the liquid
The temp is constant during the evaporation
The liquid and gas are in thermal equilibrium during evaporation
Explain the temperature increase effects on entropy when heating a gas
The S increasing when heating the gas because more rotation and new vibrations
Explain the entropy vs temp plot
Entropy vs temp
At the Tb and the Tm there is a jump in entropy but the temp stays the same
What is the equation for the energy accessible to be used as work
What is meant by reversible
Delta S = Q reversible / T
System is constantly in eqauillibrium with surrounding
No spontaneus direction of change at any point
If you have 2 things in equaillibrium, Infinitismal changes in system/surrounding with always reeqillibriate
What are reversible adiabats
What are reversible isotherms
Reversible adiabats: the entropy of the system doesn’t change
Reversible isotherm: the entropy of the system and surrounding doesn’t change
If the system is reversible and isothermal What is the equation for delta S
The change in energy is zero (delta U=0)
Delta S = nR ln (Vf/Vi)
Explain how to find microstates
The number of microstates correspond to the number of positions a thing can occupy
If two macrostates find the number of microstates and multiply them together
If all in one box only one microstate
if half and half, two microstates since each particle can end up in two possible places
Explain how to do statistical entropy to find entropy from microstates
Have one with 1 microstate and another with 2 microstates
Ohm is microstates
S = KB ln (ohm)
Delta S = kb ln (ohm2/ohm1)
If ohm is proportional to V^N
Delta S= NKb ln (V2/V1)
Explain the entropy of mixing
Explain how entropy is additive
When two ideal gasses that were intially separated are mixed together the entity increases
The S total = S system + S surroundings
What two equations do you get if you have constant pressure and constant volume with delta S
The helm holtz free energy (constant volume and temp)
The Gibbs free energy (constant pressure and temp)
What are partition functions and ensembles
Characterize entropy as the probability of a particular microstate
Also finds the energies all the particles can occupy
What does the microcanonical ensemble
Canonical
Grand canonical
Tell us
Mocrocanonical (energy can’t be exchanged out of a system)
Canocnal
Grand canonical (particles and energy are exchanged)
