E = sum kinetic energy/motion of molecule, and potential energy represented by chemical bond bet atom
∆E = q + w
∆E = Change internal energy
q = heat transfer
w = work done by/on system
Thermodynamics Study of work, heat and energy on a system
∆E universe = ∆E sys + ∆E surrounding = 0
1st Law Thermodynamics
Entropy - Measure of disorder↓
∆S uni = ∆S sys + ∆S surr > 0 (irreversible rxn)↓
All spontaneous rxn produce increase in entropy of universe
2nd Law Thermodynamics
∆S uni = ∆S sys + ∆S surr
Isolated system - Entropy change of universe always increase
Click here thermodynamics entropyEntropy
Measure molecular disorder/randomness↓
More disorder - More dispersion of matter/energy↓
More random - Rxn toward right- Entropy Increases ↑
Direction to right- Spontaneous to right →
2nd Law Thermodynamics
Embrace the chaos
Over time - Entropy increase ↑
Direction to left ← Never happen !
Click here thermodynamics
Energy cannot be created or destroyed
> 0
∆S = Entropy change
Entropy
Dispersal/DistributionMatter Energy
Matter more disperse ↑
Entropy increases ↑
solid liquid gas
spontaneous - entropy ↑
Over time - Entropy increase ↑
Phase change - sol → liq → gas↓
Entropy increase ↑
Every energy transfer - increase entropy universeEntropy universe can only go up - never go down Entropy increase - many ways energy spread out
Dispersion energy as heat - increase entropy
Stoichiometry- more gas/liq in product ↓
Entropy increase ↑
TQS
Heat added ↑Phase change Stoichiometry
Embrace the chaos
N2O4 (g) → 2NO2(g)
1 2
2H2O(l) → 2H2 (g) + O2 (g)
1 23
3
More gas in product - Entropy ↑
Heat added ↑
Entropy
Measure molecular disorder/randomness↓
More disorder - More dispersion of matter/energy↓
More randon - Rxn towards right- Entropy Increases ↑
Liq more disorder than solidGas more disorder than liq
kinetic energy distributed over wide range
Q = heat transfer
T = Temp/K
Distribution matter in space Distribution energy bet particles
Direction to left ← Never happen !Direction to right- Spontaneous to right →
TQS
StatisticalEntropy
Entropy
Measure molecular disorder/randomness↓
More disorder - More dispersion of matter/energy↓
More random - Entropy Increases ↑
1st Law Thermodynamics - Doesn't help explain direction of rxn∆S uni > 0 (+ve) → More disorder - spontaneous∆S uni < 0 (-ve) → More order - non spontaneous
Change sol → liq → gas - Higher entropyGreater number particles in product - Higher entropy
More complex molecule - More atoms bonded - Higher entropyHigher temp - Vibrate faster - More random - Higher entropy
Why gas mixes and not unmix? Why heat flow from hot to cold?
Entropy
Notes on Entropy
1st Law Thermodynamics 2nd Law Thermodynamics
Energy cannot be created or destroyedTransfer from one form to another
∆E universe = ∆E sys + ∆E surrounding = 0
Isolated system ↓
∆S uni always increase
∆E = q + w
Method to calculate entropy
Number microstates
Thermodynamic Entropy
Heat + Temp involved
Gas mixesSolution diffuse Heat flow hot →cold
X X X
∆E = internal energy
q = heat transfer
w = work done ∆S = Entropy universe
∆S = Entropy system
∆S = Entropy surrounding
∆S uni = ∆S sys + ∆S surr
Law Thermodynamics
1 2
∆S = Entropy change
Q = heat transferWkS ln
T = Temp/K∆S = Entropy change
k = boltzmann constant
W = Microstate
Click here statistical entropy Click here thermodynamics entropy
Why solution diffuse and not undiffuse?
Unit - J mol -1 K-1
1st Law Thermodynamics - Doesn't help explain direction of rxn∆S uni > 0 (+ve) → More disorder - spontaneous∆S uni < 0 (-ve) → More order - non spontaneousChange from sol → liq → gas - Higher entropy
Greater number particles in product - Higher entropyMore complex molecule - More atoms bonded - Higher entropyHigher temp - Vibrate faster - More random - Higher entropy
Measure molecular disorder/randomness↓
More disorder - More dispersion of matter/energy↓
More random - Entropy Increases ↑
Isolated system ↓
∆S uni always increase
Entropy
Why gas mixes and not unmix? Why heat flow from hot to cold?
Notes on Entropy
1st Law Thermodynamics 2nd Law Thermodynamics
Energy cannot be created or destroyedTransfer from one form to another
∆E universe = ∆E sys + ∆E surrounding = 0
∆E = q + w
Gas mixesSolution diffuse Heat flow hot →cold
X X X
∆E = internal energy
q = heat transfer
w = work done ∆S = Entropy universe
∆S = Entropy system
∆S = Entropy surrounding
∆S uni = ∆S sys + ∆S surr
Law Thermodynamics
3rd Law Thermodynamics
Unit - J mol -1 K-1
Standard Molar Entropy, S0
Entropy perfectly crystal at 0K = 0Std molar entropy, S0
↓S0 when substance heated from 0K to 298K
Std state - 1 atm / 1M sol
Temp = 298K
Std Molar Entropy/S0 S0 at 298 /JK-1 mol-1
H2O (s) + 48
H2 (g) + 130
Na (s) + 52
H2O (l) + 69
CH3OH (l) + 127
H2O (g) + 188
CO2 (g) + 218
Fe (s) + 27 Solid - Order↓
Entropy Lowest
Liq - Less order↓
Entropy Higher
Gas - Disorder↓
Entropy Highest
Entropy highest
Why solution diffuse and not undiffuse?
Entropy
Why gas mix and not unmix? Why solution diffuse and not undiffuse? Why heat flow from hot to cold?
Gas mixesSolution diffuse Heat flow hot →cold
X X X
Unit - J mol -1 K-1
Standard Molar Entropy, S0
Entropy perfectly crystal at 0K = 0↓
S0 when substance heated from 0K to 298K
Std state - 1 atm / 1M sol
Temp = 298K
Std Molar Entropy/S0 S0 at 298 /JK-1 mol-1
H2O (s) + 48
H2 (g) + 130
Na (s) + 52
H2O (l) + 69
CH3OH (l) + 127
H2O (g) + 188
CO2 (g) + 218
Fe (s) + 27 Solid - Order↓
Entropy Lowest
Liq - Less order↓
Entropy Higher
Gas - Disorder↓
Entropy Highest
Entropy highest
Entropy
Standard Molar Entropy, S0
Depends on
Temp increase ↑ - Entropy increase ↑
Physical/phase state
Dissolving solid Molecular mass
Click here thermodynamics entropy Ba(OH)2
Temp
Temp/K 273 295 298
S0 for H2 + 31 + 32 + 33.2
Sol → Liq → Gas - Entropy increase ↑
State solid liquid gas
S0 for H2O + 48 + 69 + 188
entropy increase ↑ entropy increase ↑
Depends on
Substance NaCI NH4NO3
S0 for solid + 72 + 151
S0 for aq + 115 + 260
More motion - entropy increase ↑ Higher mass - entropy increase ↑
Substance HF HCI HBr
S0 + 173 + 186 + 198
Molar mass 20 36 81
S0 = 0 at 0KAll sub > 0K, have +ve S0
Entropy perfectly crystal at 0K = 0↓
S0 when substance heated from 0K to 298K
Entropy
Why gas mix and not unmix? Why solution diffuse and not undiffuse? Why heat flow from hot to cold?
Gas mixesSolution diffuse Heat flow hot →cold
X X X
Unit - J mol -1 K-1
Standard Molar Entropy, S0
Std state - 1 atm / 1M sol
Temp = 298K
Std Molar Entropy/S0 S0 at 298 /JK-1 mol-1
H2O (s) + 48
Na (s) + 52
H2O (l) + 69
CH3OH (l) + 127
H2O (g) + 188
CO2 (g) + 218
Solid - Order↓
Entropy Lowest
Liq - Less order↓
Entropy Higher
Gas - Disorder↓
Entropy Highest
Entropy highest
Entropy
Standard Molar Entropy, S0
Depends on
Temp increase ↑ - Entropy increase ↑
Physical/phase state
Dissolving solid Molecular mass
Temp
Temp/K 273 295 298
S0 for H2 + 31 + 32 + 33.2
Sol → Liq → Gas - Entropy increase ↑
State solid liquid gas
S0 for H2O + 48 + 69 + 188
entropy increase ↑ entropy increase ↑
Depends on
More motion - entropy increase ↑
Click here entropy notes
Click here entropy, enthalpy free energy data
Click here entropy CRC data booklet
Higher mass - entropy increase ↑
S0 = 0 at 0KAll sub > 0K, have +ve S0
Substance NaCI NH4NO3
S0 for solid + 72 + 151
S0 for aq + 115 + 260
Substance HF HCI HBr
S0 + 173 + 186 + 198
Molar mass 20 36 81
N2O4 (g) → 2NO2(g)
Reactant Product
Entropy
Ice (s) Water (l)
Entropy
Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?
Method to calculate entropy
Gas mixesSolution diffuse Heat flow hot →cold
X X X
Qualitatively
Solid → Liquid NaCI(s) → Na+(aq) + CI -(aq)
N2O4 (g) → 2NO2(g)
Reactant ProductS θ Less More
More microstates (More dispersion/random/freedom of motion)
Solid → liq → gas
Higher ↑ entropy
Greater number particles in product More liq/gas in product
Dispersion Energy Microstate
More dispersion of energy(Electronic, translational, rotational, vibrational, thermal)
Higher entropy ∆S > 0 (+ve) - Spontaneous
∆Srxnθ = ∑Sf
θ(pro) - ∑Sf
θ(react)
∆Srxnθ = More - Less
= +ve > 0
S θ Less More
∆Srxnθ = ∑Sf
θ(pro) - ∑Sf
θ(react)
∆Srxnθ = More - Less
= +ve > 0
∆Srxnθ = ∑Sf
θ(pro) - ∑Sf
θ(react)
∆Srxnθ = More - Less
= +ve > 0
NaCI(s) → Na+(aq) + CI -(aq)
S θ Less MoreReactant Product
QualitativelyUnit - J mol -1 K-1
Reactant Product
Entropy
Liq N2(l) Gas N2 (g)
Entropy
Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?
Method to calculate entropy
Gas mixesSolution diffuse Heat flow hot →cold
X X X
Qualitatively
Liquid → Gas
Reactant ProductS θ Less More
More microstates (More dispersion/random/freedom of motion)
Solid → liq → gas
Higher entropy
Greater number particles in product More liq/gas in product
Dispersion Energy Microstate
More dispersion of energy(Electronic, translational, rotational, vibrational, thermal)
Higher entropy ∆S > 0 (+ve) - Spontaneous
∆Srxnθ = ∑Sf
θ(pro) - ∑Sf
θ(react)
∆Srxnθ = More - Less
= +ve > 0
S θ Less More
∆Srxnθ = ∑Sf
θ(pro) - ∑Sf
θ(react)
∆Srxnθ = More - Less
= +ve > 0
∆Srxnθ = ∑Sf
θ(pro) - ∑Sf
θ(react)
∆Srxnθ = More - Less
= +ve > 0
NH4NO3(s) → NH4+
(aq) + NO3 -(aq)
S θ Less MoreReactant Product
Qualitatively
NH4NO3 (s) → NH4 +(aq) + NO3 - (aq) Ba(OH)2 .8H2O(s) + 2NH4NO3 (s) →
Ba2+(aq) + 2NO3
-(aq) + 2NH3 (g) + 10H2O(aq)
Ba(OH)2 .8H2O(s) + 2NH4NO3 (s) → Ba2+(aq) + 2NO3
- (aq) + 2NH3 (g) +10H2O(aq)
Unit - J mol -1 K-1
+
Find entropy change when value open ?
Initial Microstate, Wi = 1 Final Microstate, Wf = 2
StatisticalEntropy
Entropy
Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?
Entropy
Method to calculate entropy
Number microstates Thermodynamic Entropy
Heat + Temp involved
Gas mixesSolution diffuse Heat flow hot →cold
X X X
1 2
∆S = Entropy change
Q = heat transfer
WkS lnT = Temp/K
S = Entropy
k = boltzmann constant
W = Microstate
Quatitatively
TQS
k = R/NA = 1.38 x 10-23 J K-1 Click here statistical entropy
1241056.9 JKS
or
∆S = S f - S i = klnWf - klnWi
i
f
WW
kS ln 2ln12ln kkS
S initial S final
Find entropy change when 334kJ heat added to melt 1kg ice to water at 273K?
Click here thermodynamic entropy
11227273334000 JKS
TQS 1 kg
Q = 334kJ
Quatitatively
Q = heat transfer
TQS
Find entropy change when value open ?
Initial Microstate, Wi = 1 Final Microstate, Wf = 4
Statistical Entropy
Entropy
Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?
Entropy
Method to calculate entropy
Thermodynamic Entropy
Gas mixesSolution diffuse Heat flow hot →cold
X X X
1 2
∆S = Entropy change
WkS lnT = Temp/K
S = Entropy k = boltzmann constant
W = Microstate
Quatitatively
1231091.1 JKS
∆S = S f - S i = klnWf - klnWi
i
f
WW
kS ln 4ln14ln kkS
S initial S final
A has 250g water at 100C and B has 250g ice at OC.Find ∆S when value open, temp of both A/B at 50C? Heat transfer A → B. Heat loss by A. Heat gain by B
125175150 JKSSS BAsys
1150348
50184.4250
JKTmc
TQSA
A100C
Quatitatively
B0C
1175298
50184.4250
JKTmc
TQSB
Assume ∆S negligible (over small range Temp)
A50C
B50C
Ave temp takenA - 100 → 50C Ave - 75C (348K)
Ave temp takenB - 0 → 50C Ave 25C (298K)
Click here statistical thermodynamicsClick here thermodynamics entropy
Entropy decrease ↓
Entropy
Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?
Predict entropy change - qualitatively
Gas mixesSolution diffuse Heat flow hot →cold
X X X
NH4NO3 (s) → NH4 +(aq) + NO3 - (aq)
C3H8(g) + 5O2 (g) → 3CO2(g) + 4H2O(g) 2H2(g) + O2 (g) → 2H2O(l)
2Cu(s) + O2 (g) → 2CuO(s)
Br2(l) → Br2(g)
Ag+(aq) + Br-
(aq) → AgBr(s) H2(g) + CI2 (g) → 2HCI(g)
Cu2+(aq) + Zn(s) → Cu(s) + Zn2+
(aq) CaCO3 (s) → CaO(s) + CO2 (g)
1
Entropy decrease ↓
Entropy decrease ↓ Entropy increase ↑
Entropy increase ↑Entropy increase ↑
Entropy increase ↑
Little change
Little change
2 3
4
Reactant Product
aq - more disorder solid - more order S higher ↑ S - Lower ↓
Reactant Product
g - more disorder solid - more order S higher ↑ S - Lower ↓
Reactant Product
Both sides equal number mol gas
Reactant Productg - more disorder liq - more order S higher ↑ S - Lower ↓
Reactant Product
liq- more order g - more disorder S Lower ↓ S - Higher↑
Reactant Product
less g- more order more g - more disorder S Lower ↓ S - Higher↑
Reactant Product
Both sides equal number mol solid
Reactant Product
solid- more order aq - more disorder S Lower ↓ S - Higher↑
Reactant Product
solid- more order g - more disorder S Lower ↓ S - Higher↑
5 6
7 8 9