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 entropy Entropy

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/Distribution Matter 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 universe Entropy 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 ↑

T

QS

Heat added ↑ Phase change Stoichiometry

Embrace the chaos

N2O4(g) → 2NO2(g)

1 2

2H2O(l) → 2H2 (g) + O2 (g)

1 2 3

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 solid Gas 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 →

Statistical Entropy

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 entropy

Greater number particles in product - Higher entropy More complex molecule - More atoms bonded - Higher entropy Higher 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 destroyed Transfer 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 mixes Solution 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 uni

WkS ln

∆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

surrsysuni SSS

∆S = Entropy sys and surr

High chaos factor

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 entropy

Greater number particles in product - Higher entropy More complex molecule - More atoms bonded - Higher entropy Higher 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 destroyed Transfer from one form to another

∆E universe = ∆E sys + ∆E surrounding = 0

∆E = q + w

Gas mixes Solution 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 = 0 Std molar entropy, S0 (absolute value)

↓ 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

Fe (s) + 27

H2O (s) + 48

Na (s) + 52

H2O (l) + 69

CH3OH (l) + 127

H2 (g) + 130

H2O (g) + 188

CO2 (g) + 218

Solid - Order

↓

Entropy Lowest

Liq - Less order

↓

Entropy Higher

Gas - Disorder

↓

Entropy Highest

Entropy highest

Why solution diffuse and not undiffuse?

High chaos factor

Entropy

Why gas mix and not unmix? Why solution diffuse and not undiffuse? Why heat flow from hot to cold?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Unit - J mol -1 K-1

Standard Molar Entropy, S0

Entropy perfectly crystal at 0K = 0 (Absolute value) ↓

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

Fe (s) + 27

H2O (s) + 48

Na (s) + 52

H2O (l) + 69

CH3OH (l) + 127

H2 (g) + 130

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

Depend 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 ↑

Depend 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

Molar mass 20 36 81

S0 + 173 + 186 + 198

S0 = 0 at 0K All sub > 0K, have +ve S0

Entropy perfectly crystal at 0K = 0 (Absolute value) ↓

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 mixes Solution 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

Depend 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 ↑

Depend 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 0K All sub > 0K, have +ve S0

Substance NaCI NH4NO3

S0 for solid + 72 + 151

S0 for aq + 115 + 260

Substance HF HCI HBr

Molar mass 20 36 81

S0 + 173 + 186 + 198

∆Hf θ (reactant) ∆Hf

θ (product)

Using Std ∆Hf θ formation to find ∆H rxn

∆H when 1 mol form from its element under std condition

Na(s) + ½ CI2(g) → NaCI (s) ∆Hf θ = - 411 kJ mol -1

Std Enthalpy Changes ∆Hθ

Std condition

Pressure 100kPa

Temp 298K

Conc 1M All substance at std states

Std ∆Hf θ formation

Mg(s) + ½ O2(g) → MgO(s) ∆Hf θ =- 602 kJ mol -1

Reactants Products

O2(g) → O2 (g) ∆Hf θ = 0 kJ mol -1

∆Hrxnθ = ∑∆Hf

θ(products) - ∑∆Hf

θ(reactants)

∆Hf θ (products) ∆Hf

θ (reactants)

∆Hrxnθ

Elements

Std state solid gas

2C(s) + 3H2(g)+ ½O2(g) → C2H5OH(I) ∆Hf θ =- 275 kJ mol -1

1 mole formed

H2(g) + ½O2(g) → H2O(I) ∆Hf θ =- 286 kJ mol -1

Std state solid gas 1 mol liquid

For element Std ∆Hf θ formation = 0

Mg(s)→ Mg(s) ∆Hf θ = 0 kJ mol -1

No product form

Using Std ∆Hf θ formation to find ∆H rxn

Click here chem database (std formation enthalpy)

Click here chem database (std formation enthalpy)

C2H4 + H2 C2H6

Find ΔHθ rxn using std ∆H formation

Reactants Products

2C + 3H2

Elements C2H4 + H2 → C2H6

∆Hrxnθ

∆Hrxnθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Hrxnθ = Hf

θ C2H6 - ∆Hf

θ C2H4+ H2 = - 84.6 – ( + 52.3 + 0 ) = - 136.9 kJ mol -1

Enthalpy Formation, ∆Hf

Std ∆Gfθ formation

∆Grxnθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Grxnθ = Gf

θ C2H6 - ∆Gf

θ C2H4+ H2 = - 33 – ( + 68 + 0 ) = - 101 kJ mol -1

∆Gf θ (reactant) ∆Gf

θ (product)

Using Std ∆Gf θ formation to find ∆G rxn o

∆Gf when 1 mol form from its element under std condition

Na(s) + ½ CI2(g) → NaCI (s) ∆Gf θ = - 384 kJ mol -1

Std Free Energy Change ∆Gθ

Std condition

Pressure 100kPa

Temp 298K

Conc 1M All substance at std states

Gibbs Free Energy change formation, ∆Gf

Mg(s) + ½ O2(g) → MgO(s) ∆Gf θ =- 560 kJ mol -1

Reactants Products

O2(g) → O2 (g) ∆Gf θ = 0 kJ mol -1

∆Grxnθ = ∑∆Gf

θ(prod) - ∑∆Gf

θ(react)

∆Gf θ (product) ∆Gf

θ (reactant)

∆Grxnθ

Elements

Std state solid gas

2C(s) + 3H2(g)+ ½O2(g) → C2H5OH(I) ∆Gf θ =- 175 kJ mol -1

1 mole formed

H2(g) + ½O2(g) → H2O(I) ∆Gf θ =- 237 kJ mol -1

Std state solid gas 1 mol liquid

For element Std ∆Gf θ formation = 0

Mg(s)→ Mg(s) ∆Gf θ = 0 kJ mol -1

No product form

Using Std ∆Gf θ formation to find ∆G rxn

Click here chem database (std ∆G formation)

Click here chem database (std ∆G formation)

C2H4 + H2 C2H6

Find ΔGθ rxn using std ∆G0 formation

Reactants Products

2C + 3H2

Elements C2H4 + H2 → C2H6

∆Grxnθ

∆S sys + ve , ∆S surr - ve

↓ ∆S uni > 0 (+ve)

(Rxn Spontaneous)

∆S sys - ve , ∆S surr + ve

↓ ∆S uni < 0 (-ve)

(Rxn Non spontaneous)

spontaneous

+ve

-ve

=

S /JK-1

∆Ssys = + ve

∆Ssurr = + ve

∆Suni = + ve

+

∆Ssys = - ve

+

∆Ssurr = + ve

∆Suni = + ve

= spontaneous

S /JK-1 S /JK-1

∆Ssys = + ve

+

∆Ssurr = - ve

=

∆Suni = + ve

spontaneous

C6H12O6(s) + 6O2 (g) → 6CO2(g) + 6H2O(l)

Using ∆Hsys , ∆Suni , ∆S sys , ∆S surr to predict spontaneity

2NO(g) + O2(g) → 2NO2(g) CaCO3 (s) → CaO(s) + CO2(g)

∆H = -ve (Heat released)

Difficult !!

∆S sys + ve , ∆S surr - ve

↓ ∆S uni < 0 (-ve)

(Rxn Non spontaneous)

∆Ssys = + ve

∆Ssurr = - ve

+ =

∆Suni = - ve

Non spontaneous

∆H = -ve (Heat released) ∆H = +ve (Heat absorb)

CaCO3 (s) → CaO(s) + CO2(g)

∆H = +ve (Heat absorb)

∆Ssys = + ve

+

∆Ssurr = - ve

∆Suni = - ve

Non spontaneous

=

H2(g) → 2 H(g)

∆H = +ve (Heat absorb)

H2O (l) → H2O(s)

∆H = -ve (Heat released)

∆Ssys = - ve

+

∆Suni = - ve

∆Ssurr = + ve

=

∆S sys + ve , ∆S surr - ve

↓ ∆S uni < 0 (-ve)

(Rxn Non spontaneous)

∆S sys + ve , ∆S surr + ve

↓ ∆S uni > 0 (+ve)

(Rxn Spontaneous)

∆S sys - ve , ∆S surr + ve

↓ ∆S uni > 0 (+ve)

(Rxn Spontaneous)

∆Hsys ∆Ssys ∆Suni Description

- + > 0 (+) Spontaneous, All Temp

+ - < 0 (-) Non spontaneous, All Temp

+ + > 0 (+) Spontaneous, High ↑ Temp

- - > 0 (+) Spontaneous, Low ↓ Temp

Predicting Spontaneity rxn

∆G - Temp/Pressure remain constant Assume ∆S/∆H constant with temp

Using ∆Hsys , ∆Suni , ∆S sys , ∆S surr to predict spontaneity Using ∆Gsys to predict spontaneity

syssyssys STHG

Difficult !!

surrsysuni SSS T

HSsurr

)()( reactfprofsys HHH

CH4(g) + 2O2 (g) → CO2(g) + 2H2O(l)

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(l) ∆Hf

0 - 74 0 - 393 - 286 x 2

S0 + 186 +205 x 2 + 213 + 171 x 2

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

1

)tan()(

41

596555

JKS

S

SSS

sys

sys

treacproductsys kJHsys 891)74(965

12990

298

)891000(

JKS

S

T

HS

surr

surr

surr

12949299041

JKS

SSS

uni

surrsysuni

∆S uni > 0 spontaneous

Easier

Unit ∆G - kJ Unit ∆S - JK-1

Unit ∆H - kJ

CH4(g) + 2O2 (g) → CO2(g) + 2H2O(l)

Only ∆S sys involved ∆S surr, ∆S uni not needed

∆Hsys ∆Ssys ∆Gsys Description

- + ∆G = ∆H - T∆S

∆G = - ve Spontaneous, All Temp

+ - ∆G = ∆H - T∆S

∆G = + ve Non spontaneous, All Temp

+ + ∆G = ∆H - T∆S

∆G = - ve Spontaneous, High ↑ Temp

- - ∆G = ∆H - T∆S

∆G = - ve Spontaneous, Low ↓ Temp

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(g) S0 + 186 +205 x 2 +213 + 188 x 2

Reactant (+596) Product (+589)

kJG

G

STHG syssyssys

888

)007.0(298890

∆Hsys = - 890 kJ kJS

JKS

S

SSS

sys

sys

sys

reactprodsys

007.0

7

596589

1

)()(

∆G < 0 spontaneous

Entropy change ∆S greater at low temp

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -868 - (-51) = - 817 kJ

Predicting Spontaneity rxn

∆G - Temp/Pressure remain constant Assume ∆S/∆H constant with temp

Using ∆Gsys to predict spontaneity

syssyssys STHG

CH4(g) + 2O2 (g) → CO2(g) + 2H2O(l)

Reactant (-51) Product (-868)

∆G < 0 spontaneous

Easier

Unit ∆G - kJ mol-1 CH4(g) + 2O2 (g) → CO2(g) + 2H2O(l)

Only ∆S sys involved ∆S surr, ∆S uni not needed

∆Hsys ∆Ssys ∆Gsys Description

- + ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at all Temp

+ - ∆G = ∆H - T ∆S

∆G = + ve Non spontaneous, all Temp

+ + ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at high ↑ Temp

- - ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at low ↓ Temp

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(g) S0 + 186 +205 x 2 +213 + 188 x 2

Reactant (+ 596) Product (+ 589)

kJG

G

STHG syssyssys

888

)007.0(298890

∆Hsys = - 890 kJ kJS

JKS

S

SSS

sys

sys

sys

reactprodsys

007.0

7

596589

1

)()(

∆G < 0 spontaneous

Using ∆Gsys to predict spontaneity

Easier

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(l) ∆G0 - 51 0 - 394 - 237 x 2

Method 1 Method 2

)()( reactfprofsys GGG

CH4(g) + 2 O2 (g) CO2(g) + 2H2O(g)

C + 2O2 + 2H2

Reactants Products ∆Gsys

θ

∆Gf θ (reactant) ∆Gf

θ (product) Elements

• Neither ∆H or ∆S can predict feasibility of spontaneous rxn • Gibbs Free Energy (∆G) – measure spontaneity and useful energy available • Gibbs Free Energy (∆G) - max amt useful work at constant Temp/Pressure • Involve ∆H sys and ∆S sys • ∆G involve only sys while ∆S uni involve sys and surr • Easier to find ∆H and ∆S for system

Gibbs Free Energy change formation, ∆Gf0

At std condition/states Temp - 298K Press - 1 atm

∆G - Temp/Pressure remain constant Assume ∆S/∆H constant with temp

Using ∆Gsys to predict spontaneity

syssyssys STHG

Easier

Unit ∆G - kJ CH4(g) + 2O2 (g) → CO2(g) + 2H2O(l)

Only ∆S sys involved ∆S surr, ∆S uni not needed

∆Hsys ∆Ssys ∆Gsys Description

- + ∆G = ∆H - T∆S

∆G = - ve Spontaneous, All Temp

+ - ∆G = ∆H - T∆S

∆G = + ve Non spontaneous, All Temp

+ + ∆G = ∆H - T∆S

∆G = - ve Spontaneous, High ↑ Temp

- - ∆G = ∆H - T∆S

∆G = - ve Spontaneous, Low ↓ Temp

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(g) S0 + 186 +205 x 2 +213 + 188 x 2

Reactant (+ 596) Product (+ 589)

kJG

G

G

STHG syssyssys

888

2890

)007.0(298890

∆Hsys = - 890 kJ

kJS

JKS

S

SSS

sys

sys

sys

reactprodsys

007.0

7

596589

1

)()(

∆G < 0 spontaneous

Gibbs Free Energy Change, ∆G

∆G sys T∆S sys

Total energy change, ∆H

Measure spontaneity and useful energy available Max amt useful work at constant Temp/Pressure

Free Energy

syssyssys STHG

Free energy available to do work not available

for work

syssyssys STHG

Free Energy

Total energy change, ∆H

∆G sys T∆S sys

-890kJ

Free energy available to do work

not available for work

-888kJ +2 kJ

Gibbs Free Energy Change, ∆G

∆G - Temp/Pressure remain constant Assume ∆S/∆H constant with temp

Using ∆Gsys to predict spontaneity

syssyssys STHG

Easier

Unit ∆G - kJ mol-1

Only ∆S sys involved ∆S surr, ∆S uni not needed

Using ∆Gsys to predict spontaneity

Easier

Method 1 Method 2

)()( reactfprofsys GGG At std condition/states

Temp - 298K Press - 1 atm

Gibbs Free Energy change formation, ∆Gf0

At High Temp ↑

Temp dependent

syssyssys STHG

At low Temp ↓

veG

STG

HST sys

syssyssys STHG

veG

HG

STH

spontaneous spontaneous

surrsysuni SSS

T

HS

sys

surr

syssysuni STHST

Deriving Gibbs Free Energy Change, ∆G

T

HSS

sys

sysuni

∆S sys / ∆H sys

multi by -T

syssyssys STHG

∆Hsys ∆Ssys ∆Gsys Description

- + ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at all Temp

+ - ∆G = ∆H - T ∆S

∆G = + ve Non spontaneous, all Temp

unisys STG syssyssys STHG

Only ∆H sys/∆S sys involved ∆S surr, ∆S uni not needed

syssyssys STHG

Non standard condition Standard condition

or

Gibbs Free Energy Change, ∆G

syssyssys STHG unisys STG

veGsys

∆S uni = +ve

Spontaneous Spontaneous

veGsys ∆H = - ve

∆S sys = +ve

∆Hsys ∆Ssys ∆Gsys Description

+ + ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at high ↑ Temp

- - ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at low ↓ Temp

kJG

G

STHG

130

)16.0(298178

Predict entropy change - quatitatively

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

kJHsys 178)1206(1028

∆G uni > 0 - Decomposition at 298K - Non Spontaneous

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

CaCO3 (s) → CaO(s) + CO2(g)

CaCO3 (s) → CaO (s) + CO2(g) ∆Hf

0 - 1206 - 635 - 393 S0 + 93 + 40 + 213

kJS

S

S

SSS

sys

sys

sys

treacproductsys

16.0

160

93253

)tan()(

Decomposition at 298K Decomposition at 1500K

CaCO3 (s) → CaO(s) + CO2(g)

CaCO3 (s) → CaO (s) + CO2(g) ∆Hf

0 - 1206 - 635 - 393 S0 + 93 + 40 + 213

kJHsys 178)1206(1028

Rxn Temp dependent Spontaneous at High ↑ temp

Decomposition limestone CaCO3 spontaneous?

Gibbs Free Energy Change, ∆G

kJS

S

S

SSS

sys

sys

sys

treacproductsys

16.0

160

93253

)tan()(

kJG

G

STHG

62

)16.0(1500178

∆G uni < 0 - Decomposition at 1500K - Spontaneous

∆H = +ve ∆S = +ve

Temp dependent

∆Hsys ∆Ssys ∆Gsys Description

+ + ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at high ↑ Temp

- - ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at low ↓ Temp

At Low Temp At High Temp

Predict entropy change - quatitatively

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆G uni > 0 - Decomposition at 298K - Non Spontaneous

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

Rxn Temp dependent Spontaneous at Low ↓ temp

Gibbs Free Energy Change, ∆G

∆G uni < 0 - Decomposition at 1500K - Spontaneous

∆H = - ve ∆S = - ve

Temp dependent

∆Hsys ∆Ssys ∆Gsys Description

+ + ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at high ↑ Temp

- - ∆G = ∆H - T ∆S

∆G = - ve Spontaneous at low ↓ Temp

H2O (l) → H2O(s)

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

Freezing at 298K (25C)

Is Freezing spontaneous?

kJHsys 6)286(292

kJS

S

S

SSS

sys

sys

sys

treacproductsys

02.0

22

7048

)tan()(

kJG

G

STHG

55.0

)022.0(2986

Freezing at 263K (-10C)

H2O (l) → H2O(s)

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

kJHsys 6)286(292

kJS

S

S

SSS

sys

sys

sys

treacproductsys

02.0

22

7048

)tan()(

kJG

G

STHG

21.0

)022.0(2636

At High Temp At Low Temp

C3H8(g) + 5 O2 (g) 3CO2(g) + 4H2O(l)

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1

syssyssys STHG

)tan()( treacprosys SSS

C3H8(g) + 5O2 (g) → 3CO2(g) + 4H2O(l) ∆H = -2220 kJ at 298K

C3H8(g) + 5 O2 (g) → 3 CO2(g) + 4 H2O(l) S0 +270 +205 x 5 +213 x 3 +70 x 4

1295 919 Reactant Product

kJG

G

STHG

2108

)376.0(2982220

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

376.0

376

1295919

1

)tan()(

∆H = -2220 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Is Combustion at 298K spontaneous?

Using Free Energy to predict spontaneity

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -2130 - (-23) = - 2153 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - Combustion at 298K - Spontaneous

C3H8(g) + 5 O2 (g) → 3 CO2(g) + 4 H2O(l) ∆G0 - 23 0 - 394 x 3 - 237 x 4

Elements

3C + 5O2 + 4H2

Reactant (-23) Product (-2130)

∆G < 0 - Combustion at 298K - Spontaneous

CH4(g) + 2O2 (g) → CO2(g) + 2H2O(g) ∆H = - 890 kJ at 298K

CH4(g) + 2 O2 (g) CO2(g) + 2H2O(g)

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

2

syssyssys STHG

)tan()( treacprosys SSS

+ 596 + 589 Reactant Product

kJG

G

STHG

888

)007.0(298890

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

007.0

7

596589

1

)tan()(

∆H = - 890 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Is Combustion at 298K spontaneous?

Using Free Energy to predict spontaneity

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -868 - (-51) = - 817 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - Combustion at 298K - Spontaneous

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(l) ∆G0 - 51 0 - 394 - 237 x 2

Elements

C + 2O2 + 2H2

Reactant (-51) Product (-868)

∆G < 0 - Combustion at 298K - Spontaneous

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(g) S0 + 186 +205 x 2 +213 + 188 x 2

H2O (g) → H2O(l) ∆H = - 44.1 kJ at 298K

H2O(g) H2O(l)

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 188 + 70 Reactant Product

kJG

G

STHG

1.9

)118.0(2981.44

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

118.0

118

18870

1

)tan()(

∆H = - 44.1 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -237 - (-228) = - 9 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - Combustion at 298K - Spontaneous

H2O(g) → H2O(l) ∆G0 -228 - 237

Elements

H2 + O2

Reactant (-228) Product (-237)

∆G < 0 - Combustion at 298K - Spontaneous

Condensation steam at 298K (25C) spontaneous?

H2O (g) → H2O(l) S0 + 188 + 70

3

Using Free Energy to predict spontaneity

H2(g) → 2 H(g) ∆H = + 436 kJ at 298K

H2(g) 2H(g)

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 130 + 230 Reactant Product

kJG

G

STHG

406

)1.0(298436

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

1.0

100

130230

1

)tan()(

∆H = + 436 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = + 406 - (0) = +406 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G > 0 - Atomization at 298K - Non Spontaneous

H2(g) → 2H(g) ∆G0 0 + 203 x 2

Elements

H2

Reactant (0) Product ( + 406)

4 Is Atomization of H2 at 298K spontaneous?

H2 (g) → 2 H(g) S0 + 130 + 115 x 2

∆G > 0 - Atomization at 298K - Non Spontaneous

Using Free Energy to predict spontaneity

H2O (l) → H2O(s) ∆H = - 6 kJ at 298K

H2O(l) H2O(s)

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

2

syssyssys STHG

)tan()( treacprosys SSS

+ 70 + 48 Reactant Product

kJG

G

STHG

55.0

)022.0(2986

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

022.0

22

7048

1

)tan()(

∆H = - 6 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -236.6 - (-237) = + 0.4kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G > 0 -Freezing at 298K - Non Spontaneous

H2O(l) → H2O(s) ∆G0 -237 - 236.6

Elements

H2 + O2

Reactant (-237) Product (-236.6)

5

H2O (l) → H2O(s) S0 + 70 + 48

∆G > 0 -Freezing at 298K - Non Spontaneous

Is Freezing water to ice at 298K (25C) spontaneous?

Using Free Energy to predict spontaneity

H2O (l) → H2O(s) ∆H = - 6 kJ at 263K

H2O(l) H2O(s)

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

2

syssyssys STHG

)tan()( treacprosys SSS

+ 70 + 48 Reactant Product

kJG

G

STHG

21.0

)022.0(2636

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

022.0

22

7048

1

)tan()(

∆H = - 6 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -237.2 - (-237) = - 0.2 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 -Freezing at 263K - Spontaneous

H2O(l) → H2O(s) ∆G0 -237 - 237.2

Elements

H2 + O2

Reactant (-237) Product (-237.2)

6

H2O (l) → H2O(s) S0 + 70 + 48

∆G < 0 -Freezing at 263K - Spontaneous

Is Freezing water to ice at 263K (-10C) spontaneous?

Assume std condition at 263K

Using Free Energy to predict spontaneity

CaCO3 (s) → CaO(s) + CO2(g) ∆H = + 178 kJ at 298K

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 93 + 253 Reactant Product

kJG

G

STHG

130

)16.0(298178

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

16.0

160

93253

1

)tan()(

∆H = + 178 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = - 999 - (- 1129) = + 130 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G > 0 - Decomposition at 298K - Non Spontaneous

CaCO3(s) → CaO + CO2(g) ∆G0 -1129 - 604 - 395

Elements

Ca + C + O2

Reactant ( -1129) Product (- 999)

7 Decomposition CaCO3 at 298K (25C) spontaneous?

CaCO3 (s) → CaO (s) + CO2(g) S0 + 93 + 40 + 213

∆G > 0 - Decomposition at 298K - Non Spontaneous

CaCO3 (s) CaO (s) + CO2(g)

Using Free Energy to predict spontaneity

CaCO3 (s) → CaO(s) + CO2(g) ∆H = + 178 kJ at 1500K

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 93 + 253 Reactant Product

kJG

G

STHG

62

)16.0(1500178

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

16.0

160

93253

1

)tan()(

∆H = + 178 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = - 999 - (- 939) = - 60 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - Decomposition at 1500K - Spontaneous

CaCO3(s) → CaO + CO2(g) ∆G0 -939 - 604 - 395

Elements

Ca + C + O2

Reactant (- 939) Product (- 999)

8

CaCO3 (s) → CaO (s) + CO2(g) S0 + 93 + 40 + 213

CaCO3 (s) CaO (s) + CO2(g)

Decomposition CaCO3 at 1500K (1227C) spontaneous?

∆G < 0 - Decomposition at 1500K - Spontaneous

Assume std condition at 1500K

Using Free Energy to predict spontaneity

2NO(g) + O2(g) → 2NO2(g) ∆H = - 114 kJ at 298K

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 522 + 480 Reactant Product

kJG

G

STHG

101

)042.0(298114

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

042.0

42

522480

1

)tan()(

∆H = - 114 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = + 104 - (174) = - 70 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - Decomposition at 298K - Spontaneous

2 NO + O2 → 2NO2(g) ∆G0 + 87 x 2 0 + 52 x 2

Elements

N2 + O2

Reactant (+ 174) Product (+ 104)

9

2 NO(g) + O2 (g) 2NO2(g)

∆G < 0 - Decomposition at 298K - Spontaneous

Is Oxidation of NO at 298K (25C) spontaneous?

2 NO(g) + O2 (g) → 2NO2(g) S0 + 210 x 2 + 102 + 240 x 2

Using Free Energy to predict spontaneity

N2(g) + 3H2(g) → 2NH3(g) ∆H = - 92 kJ at 298K

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 585 + 384 Reactant Product

kJG

G

STHG

32

)2.0(29892

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

2.0

201

585384

1

)tan()(

∆H = - 92 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = - 34 - (0) = - 34 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - NH3 production at 298K - Spontaneous

N2 + 3H2 → 2NH3(g) ∆G0 0 0 - 17 x 2

Elements

N2 + H2

Reactant (0) Product (- 34)

10

N2(g) + 3H2 (g) 2NH3(g)

Is Haber, NH3 production 298K (25C) spontaneous?

NH3

N2(g) + 3H2 (g) → 2NH3(g) S0 + 192 + 131 x 3 + 192 x 2

∆G < 0 - NH3 production at 298K - Spontaneous

Using Free Energy to predict spontaneity

Fe2O3(s) + 2AI(s) → 2Fe(s) + AI2O3(s) ∆H = - 851 kJ at 298K

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 143 + 105 Reactant Product

kJG

G

STHG

840

)038.0(298851

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

038.0

38

143105

1

)tan()(

∆H = - 851 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -1576 - (-741) = - 835 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - AI production at 298K - Spontaneous

Fe2O3 + 2AI → 2Fe + AI2O3 ∆G0 - 741 0 0 - 1576

Elements

Fe + AI + O2

Reactant (-741) Product (- 1576)

11 Is Thermite, AI production 298K (25C) spontaneous?

Fe2O3(s) + 2AI(s) → 2Fe(s) + AI2O3(s) S0 + 87 + 28 x 2 + 27 x 2 + 51

∆G < 0 - AI production at 298K - Spontaneous

Fe2O3(s) + 2AI(s) 2Fe(s) + AI2O3(s)

Using Free Energy to predict spontaneity

4KCIO3(s) → 3KCIO4(s) + KCI(s) ∆H = - 144 kJ at 298K

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 572 + 535 Reactant Product

kJG

G

STHG

133

)037.0(298144

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

037.0

37

572535

1

)tan()(

∆H = - 144 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -1317 - (-1160) = - 157 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 - Decomposition at 298K - Spontaneous

4KCIO3 → 3 KCIO4 + KCI ∆G0 - 290 x 4 - 303 x 3 - 408

Elements

K + CI2 + O2

Reactant (-1160) Product (- 1317)

13

∆G < 0 - Decomposition at 298K - Spontaneous

Is decomposition KCIO3

298K (25C) spontaneous?

4KCIO3(s) → 3KCIO4(s) + KCI(s) S0 + 143 x 4 + 151 x 3 + 82

4KCIO3(s) 3KCIO4(s) + KCI(s)

Using Free Energy to predict spontaneity

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Will rxn be spontaneous ?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

syssyssys STHG

)tan()( treacprosys SSS

+ 821 + 1698 Reactant Product

kJG

G

STHG

3071

)877.0(2982810

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

877.0

877

8211698

1

)tan()(

∆H = - 2810 kJ

Assume ∆S, ∆H at constant over Temp

∆G sys < 0 (-ve) → Spontaneous ∆G sys > 0 (+ve) → Non spontaneous

Gibbs Free Energy, ∆G

syssyssys STHG

Unit ∆S - JK-1

Unit ∆H - kJ Unit ∆G - kJ

Reactants Products

∆Gsysθ = ∑∆Gf

θ(pro) - ∑∆Gf

θ(react)

∆Gsysθ = -3792 - (-910) = - 2882 kJ

∆Gsysθ

∆Gf θ (reactant) ∆Gf

θ (product)

)()( reactfprofsys GGG

∆G < 0 Combustion sugar at 298K - Spontaneous

Elements

C + H2 + O2

Reactant (-910) Product (- 3792)

14

Is combustion sugar

298K (25C) spontaneous? C6H12O6(s) + 6O2 (g) → 6CO2(g) + 6H2O(l) ∆H = - 2810 kJ at 298K

C6H12O6 (s) + 6O2(g) → 6CO2(g) + 6H2O(l) S0 + 209 +102 x 6 + 213 x 6 + 70 x 6

∆G < 0 Combustion sugar at 298K - Spontaneous

C6H12O6 + 6O2 6CO2 + 6H2O(l)

C6H12O6 (s) + 6O2(g) → 6CO2(g) + 6H2O(l) ∆G0 - 910 0 - 395 x 6 - 237 x 6

Using Free Energy to predict spontaneity

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Predict ∆G change - quatitatively

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

CH4(g) + 2O2 (g) → CO2(g) + 2H2O(l)

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(l) ∆Hf

0 - 74 0 - 393 - 286 x 2

S0 + 186 +205 x 2 +213 + 171 x 2

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

041.0

41

596555

1

)tan()(

kJH sys 890)74(964

Is Combustion at 298K spontaneous?

Unit for ∆S - JK-1 Unit for ∆H - kJ C3H8(g) + 5O2 (g) → 3CO2(g) + 4H2O(l)

C3H8(g) + 5 O2 (g) → 3 CO2(g) + 4 H2O(l) ∆Hf

0 - 104 0 - 393 x 3 - 286 x 4 S0 +270 +205 x 5 + 213 x 3 + 171 x 4

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

028.0

28

12951323

1

)tan()(

kJHsys 2219)104(2323

1 2

kJG

G

STHG

877

)041.0(298890

∆G < 0 Combustion sugar at 298K - Spontaneous

kJG

G

STHG

881

)028.0(2982219

∆G < 0 Combustion sugar at 298K - Spontaneous

Entropy and Gibbs Free Energy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

118.0

118

18870

1

)tan()(

kJHsys 44)242(286

Is Condensation/Freezing at 298K spontaneous?

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

022.0

22

7048

1

)tan()(

kJHsys 6)286(292

3 4 H2O (g) → H2O(l) H2O (l) → H2O(s)

H2O (g) → H2O(l) ∆Hf

0 - 242 - 286 S0 + 188 + 70

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

kJG

G

STHG

1.9

)118.0(2981.44

∆G < 0 Condensation at 298K - Spontaneous

kJG

G

STHG

55.0

)022.0(2986

∆G > 0 Freezing at 298K – Non Spontaneous

Entropy and Gibbs Free Energy

Predict ∆G change - quatitatively

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

kJHsys 92)0(92

Are these rxn at 298K spontaneous?

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsys

θ = ∑∆Hfθ

(pro) - ∑∆Hfθ

(react)

kJHsys 168)1564(1732

5 6 N2(g) + 3H2(g) → 2NH3(g)

N2(g) + 3H2 (g) → 2NH3(g) ∆Hf

0 0 0 - 46 x 2 S0 + 192 + 131 x 3 + 192 x 2

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

201.0

201

585384

1

)tan()(

4KCIO3(s) → 3KCIO4(s) + KCI(s)

4KCIO3(s) → 3KCIO4(s) + KCI(s) ∆Hf

0 - 391 x 4 - 432 x 3 - 436 S0 + 143 x 4 + 151 x 3 + 82

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

037.0

37

572535

1

)tan()(

kJG

G

STHG

32

)2.0(29892

∆G < 0 NH3 production at 298K - Spontaneous

kJG

G

STHG

157

)037.0(298168

∆G < 0 KCIO3 production at 298K - Spontaneous

Entropy and Gibbs Free Energy

Predict ∆G change - quatitatively

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

kJHsys 178)1206(1028

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsys

θ = ∑∆Hfθ

(pro) - ∑∆Hfθ

(react)

7 8 CaCO3 (s) → CaO(s) + CO2(g)

CaCO3 (s) → CaO (s) + CO2(g) ∆Hf

0 - 1206 - 635 - 393 S0 + 93 + 40 + 213

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

16.0

160

93253

1

)tan()(

Decomposition at 298K Decomposition at 1500K

CaCO3 (s) → CaO(s) + CO2(g)

CaCO3 (s) → CaO (s) + CO2(g) ∆Hf

0 - 1206 - 635 - 393 S0 + 93 + 40 + 213

kJHsys 178)1206(1028

Rxn Temp dependent Spontaneous at High ↑ temp

Decomposition limestone CaCO3 spontaneous?

kJG

G

STHG

130

)16.0(298178

∆G > 0 Decomposition at 298K – Non Spontaneous

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

16.0

160

93253

1

)tan()(

kJG

G

STHG

62

)16.0(1500178

∆G < 0 Decomposition at 1500 K - Spontaneous

At Low Temp At High Temp

Entropy and Gibbs Free Energy

Predict ∆G change - quatitatively

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

022.0

22

7048

1

)tan()(

kJHsys 6)286(292

Is Freezing spontaneous?

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

kJS

JKS

S

SSS

sys

sys

sys

treacproductsys

022.0

22

7048

1

)tan()(

kJHsys 6)286(292

9 10 H2O (l) → H2O(s) H2O (l) → H2O(s)

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

Freezing at 298K (25C) Freezing at 263K (-10C)

Rxn Temp dependent Spontaneous at Low ↓ temp

kJG

G

STHG

55.0

)022.0(2986

∆G > 0 Freezing at 298K – Non Spontaneous

kJG

G

STHG

21.0

)022.0(2636

∆G < 0 Freezing at 263K – Spontaneous

At High Temp At Low Temp

Entropy and Gibbs Free Energy

Predict ∆G change - quatitatively

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order - Less number gas ↓

Entropy surr ↑ increase - Heat release increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Combustion at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

C3H8(g) + 5O2 (g) → 3CO2(g) + 4H2O(l) ∆H = -2220 kJ at 298K

C3H8(g) + 5 O2 (g) → 3 CO2(g) + 4 H2O(l) S0 +270 +205 x 5 +213 x 3 +70 x 4

1295 919 Reactant Product

17450

298

)2220000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

376

1295919

JKS

S

SSS

sys

sys

treacproductsys

170747450376

JKS

SSS

uni

surrsysuni

∆H = -2220 kJ = -2220000J

surrsysuni SSS

S /JK-1

Assume Q = H at constant pressure

+ve

-ve

spontaneous ∆Ssys = - 376

∆Ssurr = +7450

= +

∆Suni = + 7074

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is Combustion at 298K spontaneous?

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order - Less number gas ↓

Entropy surr ↑ increase - Heat released increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Combustion at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

CH4(g) + 2O2 (g) → CO2(g) + 2H2O(g) ∆H = - 890 kJ at 298K

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(g) S0 + 186 +205 x 2 +213 + 188 x 2

+ 596 + 589 Reactant Product

12986

298

)890000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

7

596589

JKS

S

SSS

sys

sys

treacproductsys

1297929867

JKS

SSS

uni

surrsysuni

∆H = - 890 kJ = - 890 000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous ∆Ssys = - 7

∆Ssurr = + 2986

= +

∆Suni = + 2979

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Assume Q = H at constant pressure

Is Combustion at 298K spontaneous?

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order - Liquid form ↓

Entropy surr ↑ increase - Heat released increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Condensation at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

H2O (g) → H2O(l) ∆H = - 44.1 kJ at 298K

H2O (g) → H2O(l) S0 + 188 + 70

+ 188 + 70 Reactant Product

1148

298

)44100(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

118

18870

JKS

S

SSS

sys

sys

treacproductsys

130148118

JKS

SSS

uni

surrsysuni

∆H = -44.1 kJ = - 44 100J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = - 118

∆Ssurr = + 148

= +

∆Suni = + 30

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Condensation steam at 298K (25C) spontaneous?

Assume Q = H at constant pressure

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↑ increase - More disorder - More gas atoms form ↓

Entropy surr ↓ decrease - Heat absorb decrease ↓ motion surr particles ↓

Heat absorb by sys from surr decrease ↓ entropy surr ↓

∆S surr < ∆S sys (More -ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni < 0 - Atomization at 298K - Non Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

H2(g) → 2 H(g) ∆H = + 436 kJ at 298K

H2 (g) → 2 H(g) S0 + 130 + 115 x 2

+ 130 + 230 Reactant Product

11463

298

)436000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

100

130230

JKS

S

SSS

sys

sys

treacproductsys

113631463100

JKS

SSS

uni

surrsysuni

∆H = + 436 kJ = + 436 000J

surrsysuni SSS

S /JK-1

+ve

-ve

non - spontaneous

∆Ssys = +100

∆Ssurr = - 1463

= +

∆Suni = - 1363

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is Atomization of H2 at 298K spontaneous?

Assume Q = H at constant pressure

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order - Solid form ↓

Entropy surr ↑ increase - Heat released increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S sys > ∆S surr (More -ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni < 0 - Freezing at 298K - Non Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

H2O (l) → H2O(s) ∆H = - 6 kJ at 298K

H2O (l) → H2O(s) S0 + 70 + 48

+ 70 + 48 Reactant Product

120

298

)6000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

22

7048

JKS

S

SSS

sys

sys

treacproductsys

122022

JKS

SSS

uni

surrsysuni

∆H = -6 kJ = - 6000J

surrsysuni SSS

S /JK-1

+ve

-ve

non - spontaneous

∆Ssys = - 22

∆Ssurr = + 20

= + ∆Suni= - 2

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is Freezing water to ice at 298K (25C) spontaneous?

Assume Q = H at constant pressure

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order - Solid form ↓

Entropy surr ↑ increase - Heat released increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Freezing at 263K (-10C) - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

H2O (l) → H2O(s) ∆H = - 6 kJ at 263K

H2O (l) → H2O(s) S0 + 70 + 48

+ 70 + 48 Reactant Product

18.22

263

)6000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

22

7048

JKS

S

SSS

sys

sys

treacproductsys

18.08.2222

JKS

SSS

uni

surrsysuni

∆H = -6 kJ = - 6000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = - 22

∆Ssurr = + 22.8

= + ∆Suni= + 0.8

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is Freezing water to ice at 263K (-10C) spontaneous?

Assume Q = H at constant pressure

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↑ increase - More disorder - Gas form ↓

Entropy surr ↓ decrease - Heat absorb decrease ↓ motion surr particles ↓

Heat absorb by sys from surr decrease ↓ entropy surr ↓

∆S surr < ∆S sys (More -ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni < 0 - Decomposition at 298K - Non Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

CaCO3 (s) → CaO(s) + CO2(g) ∆H = + 178 kJ at 298K

CaCO3 (s) → CaO (s) + CO2(g) S0 + 93 + 40 + 213

+ 93 + 253 Reactant Product

1597

298

)178000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

160

93253

JKS

S

SSS

sys

sys

treacproductsys

1437597160

JKS

SSS

uni

surrsysuni

∆H = + 178 kJ =+ 178 000J

surrsysuni SSS

S /JK-1

+ve

-ve

non - spontaneous

∆Ssys = + 160

∆Ssurr = - 597

= +

∆Suni= - 437

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Decomposition CaCO3 at 298K (25C) spontaneous?

Assume Q = H at constant pressure

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↑ increase - More disorder - Gas form ↓

Entropy surr ↓ decrease - Heat aborb decrease ↓ motion surr particles ↓

Heat absorb by sys from surr decrease ↓ entropy surr ↓

∆S sys > ∆S surr (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Decomposition at 1500K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

CaCO3 (s) → CaO(s) + CO2(g) ∆H = + 178 kJ at 1500K

CaCO3 (s) → CaO (s) + CO2(g) S0 + 93 + 40 + 213

+ 93 + 253 Reactant Product

1118

1500

)178000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

160

93253

JKS

S

SSS

sys

sys

treacproductsys

142118160

JKS

SSS

uni

surrsysuni

∆H = + 178 kJ =+ 178 000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = + 160

∆Ssurr = - 118

= + ∆Suni = + 42

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Decomposition CaCO3 at 1500K (1227C) spontaneous?

Assume Q = H at constant pressure

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order - Less gas form ↓

Entropy surr ↑ increase - Heat release increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Oxidation at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

2NO(g) + O2(g) → 2NO2(g) ∆H = - 114 kJ at 298K

2 NO(g) + O2 (g) → 2NO2(g) S0 + 210 x 2 + 102 + 240 x 2

+ 522 + 480 Reactant Product

1382

298

)114000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

42

522480

JKS

S

SSS

sys

sys

treacproductsys

133938242

JKS

SSS

uni

surrsysuni

∆H = - 114 kJ = - 114 000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = - 42

∆Ssurr = + 382

= +

∆Suni = + 339

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is Oxidation of NO at 298K (25C) spontaneous?

Assume Q = H at constant pressure

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order - Less gas form ↓

Entropy surr ↑ increase - Heat release increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - NH3 production at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

N2(g) + 3H2(g) → 2NH3(g) ∆H = - 92 kJ at 298K

N2(g) + 3H2 (g) → 2NH3(g) S0 + 192 + 131 x 3 + 192 x 2

+ 585 + 384 Reactant Product

1308

298

)92000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

201

585384

JKS

S

SSS

sys

sys

treacproductsys

1107308201

JKS

SSS

uni

surrsysuni

∆H = - 92 kJ = - 92 000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = - 201

∆Ssurr = + 308

= +

∆Suni = + 107

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is Haber, NH3 production 298K (25C) spontaneous?

Assume Q = H at constant pressure

NH3

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order ↓

Entropy surr ↑ increase - Heat release increase ↑ motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - AI production at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

Fe2O3(s) + 2AI(s) → 2Fe(s) + AI2O3(s) ∆H = - 851 kJ at 298K

+ 143 + 105 Reactant Product

12855

298

)851000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

38

143105

JKS

S

SSS

sys

sys

treacproductsys

12817285538

JKS

SSS

uni

surrsysuni

∆H = - 851 kJ = - 851 000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = - 38

∆Ssurr = + 2855

= +

∆Suni = + 2817

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is Thermite, AI production 298K (25C) spontaneous?

Assume Q = H at constant pressure

Fe2O3(s) + 2AI(s) → 2Fe(s) + AI2O3(s) S0 + 87 + 28 x 2 + 27 x 2 + 51

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↓ decrease - More order ↓

Entropy surr ↑ increase - Heat release increase motion surr particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr > ∆S sys (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Decomposition KCIO3 at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

4KCIO3(s) → 3KCIO4(s) + KCI(s) ∆H = - 144 kJ at 298K

+ 572 + 535 Reactant Product

1483

298

)144000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

37

572535

JKS

S

SSS

sys

sys

treacproductsys

144648337

JKS

SSS

uni

surrsysuni

∆H = - 144 kJ = - 144 000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = - 37

∆Ssurr = + 483

= +

∆Suni = + 446

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is decomposition KCIO3

298K (25C) spontaneous?

Assume Q = H at constant pressure

∆S/∆H constant over range of temp

4KCIO3(s) → 3KCIO4(s) + KCI(s) S0 + 143 x 4 + 151 x 3 + 82

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Entropy

Thermodynamic Entropy

Gas mixes Solution diffuse Heat flow hot →cold

X X X

1 Quatitatively

T

H

T

QSsurr

Quatitatively

Entropy sys ↑ increase - More disorder ↓

Entropy surr ↑ increase - Heat release increase ↑ motion particles ↓

Heat release by sys to surr increase ↑ entropy surr ↓

∆S surr + ∆S sys > 0 (More +ve) ↓

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 Combustion sugar at 298K - Spontaneous

surrsysuni SSS

)tan()( treacprosys SSS

C6H12O6(s) + 6O2 (g) → 6CO2(g) + 6H2O(l) ∆H = - 2810 kJ at 298K

+ 821 + 1698 Reactant Product

19430

298

)2810000(

JKS

S

T

HS

surr

surr

surr

1

)tan()(

877

8211698

JKS

S

SSS

sys

sys

treacproductsys

1103079430877

JKS

SSS

uni

surrsysuni

∆H = - 2810 kJ = - 2810 000J

surrsysuni SSS

S /JK-1

+ve

-ve

spontaneous

∆Ssys = + 877

∆Ssurr = + 9430

= +

∆Suni = + 10307

∆S uni > 0 (+ve) → Spontaneous ∆S uni < 0 (-ve) → Non spontaneous

Is combustion sugar

298K (25C) spontaneous?

Assume Q = H at constant pressure

∆S/∆H constant over range of temp

C6H12O6 (s) + 6O2(g) → 6CO2(g) + 6H2O(l) S0 + 209 +102 x 6 + 213 x 6 + 70 x 6

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Predict entropy change - quatitatively

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

CH4(g) + 2O2 (g) → CO2(g) + 2H2O(l)

CH4(g) + 2 O2 (g) → CO2(g) + 2 H2O(l) ∆Hf

0 - 74 0 - 393 - 286 x 2

S0 + 186 +205 x 2 + 213 + 70 x 2

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

1

)tan()(

243

596353

JKS

S

SSS

sys

sys

treacproductsys

12990

298

)891000(

JKS

S

T

HS

surr

surr

surr

kJHsys 891)74(965

surrsysuni SSS

127472990243

JKS

SSS

uni

surrsysuni

Is Combustion at 298K spontaneous?

Unit for ∆S - JK-1 Unit for ∆H - kJ

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Combustion at 298K - Spontaneous

C3H8(g) + 5O2 (g) → 3CO2(g) + 4H2O(l)

C3H8(g) + 5 O2 (g) → 3 CO2(g) + 4 H2O(l) ∆Hf

0 - 104 0 - 393 x 3 - 286 x 4 S0 +270 +205 x 5 +213 x 3 + 70 x 4

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

1

)tan()(

376

1295919

JKS

S

SSS

sys

sys

treacproductsys kJHsys 2219)104(2323

17446

298

)2219000(

JKS

S

T

HS

surr

surr

surr

surrsysuni SSS

170707446376

JKS

SSS

uni

surrsysuni

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Combustion at 298K - Spontaneous

1 2

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Predict entropy change - quatitatively

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

1

)tan()(

118

18870

JKS

S

SSS

sys

sys

treacproductsys

1148

298

)44000(

JKS

S

T

HS

surr

surr

surr

kJHsys 44)242(286

surrsysuni SSS

130148118

JKS

SSS

uni

surrsysuni

Is Condensation/Freezing at 298K spontaneous?

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Condensation at 298K - Spontaneous

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

1

)tan()(

22

7048

JKS

S

SSS

sys

sys

treacproductsys kJHsys 6)286(292

120

298

)6000(

JKS

S

T

HS

surr

surr

surr

surrsysuni SSS

122022

JKS

SSS

uni

surrsysuni

∆S uni = ∆S sys + ∆S surr ↓

∆S uni < 0 -Freezing at 298K - Non Spontaneous

3 4 H2O (g) → H2O(l) H2O (l) → H2O(s)

H2O (g) → H2O(l) ∆Hf

0 - 242 - 286 S0 + 188 + 70

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Predict entropy change - quatitatively

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

1308

298

)92000(

JKS

S

T

HS

surr

surr

surr

kJHsys 92)0(92

surrsysuni SSS

1107308201

JKS

SSS

uni

surrsysuni

Are these rxn at 298K spontaneous?

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - NH3 production at 298K - Spontaneous

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

kJHsys 168)1564(1732

1563

298

)168000(

JKS

S

T

HS

surr

surr

surr

surrsysuni SSS

152656337

JKS

SSS

uni

surrsysuni

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Decomposition at 298K - Spontaneous

5 6 N2(g) + 3H2(g) → 2NH3(g)

N2(g) + 3H2 (g) → 2NH3(g) ∆Hf

0 0 0 - 46 x 2 S0 + 192 + 131 x 3 + 192 x 2

1

)tan()(

201

585384

JKS

S

SSS

sys

sys

treacproductsys

4KCIO3(s) → 3KCIO4(s) + KCI(s)

4KCIO3(s) → 3KCIO4(s) + KCI(s) ∆Hf

0 - 391 x 4 - 432 x 3 - 436 S0 + 143 x 4 + 151 x 3 + 82

1

)tan()(

37

572535

JKS

S

SSS

sys

sys

treacproductsys

1118

1500

)178000(

JKS

S

T

HS

surr

surr

surr

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Predict entropy change - quatitatively

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

kJHsys 178)1206(1028

surrsysuni SSS

1437597160

JKS

SSS

uni

surrsysuni

∆S uni = ∆S sys + ∆S surr ↓

∆S uni < 0 - Decomposition at 298K - Non Spontaneous

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

surrsysuni SSS

142118160

JKS

SSS

uni

surrsysuni

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 - Decomposition at 1500K - Spontaneous

7 8 CaCO3 (s) → CaO(s) + CO2(g)

CaCO3 (s) → CaO (s) + CO2(g) ∆Hf

0 - 1206 - 635 - 393 S0 + 93 + 40 + 213

1

)tan()(

160

93253

JKS

S

SSS

sys

sys

treacproductsys

Decomposition at 298K Decomposition at 1500K

CaCO3 (s) → CaO(s) + CO2(g)

CaCO3 (s) → CaO (s) + CO2(g) ∆Hf

0 - 1206 - 635 - 393 S0 + 93 + 40 + 213

1

)tan()(

160

93253

JKS

S

SSS

sys

sys

treacproductsys kJHsys 178)1206(1028

Rxn Temp dependent Spontaneous at High ↑Temp

Decomposition limestone CaCO3 spontaneous?

1597

298

)178000(

JKS

S

T

HS

surr

surr

surr

Entropy

Why gas mixes and not unmix? Why conc solution diffuse and not undiffuse? Why heat flow from hot to cold?

Predict entropy change - quatitatively

Gas mixes Solution diffuse Heat flow hot →cold

X X X

Reactant Product

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

1

)tan()(

22

7048

JKS

S

SSS

sys

sys

treacproductsys kJHsys 6)286(292

surrsysuni SSS

122022

JKS

SSS

uni

surrsysuni

Is Freezing spontaneous?

∆S uni = ∆S sys + ∆S surr ↓

∆S uni < 0 - Freezing at 298K - Non Spontaneous

Reactant Product

∆Ssysθ = ∑Sf

θ(pro) - ∑Sf

θ(react)

∆Hsysθ = ∑∆Hf

θ(pro) - ∑∆Hf

θ(react)

1

)tan()(

22

7048

JKS

S

SSS

sys

sys

treacproductsys kJHsys 6)286(292

18.22

263

)6000(

JKS

S

T

HS

surr

surr

surr

surrsysuni SSS

18.08.2222

JKS

SSS

uni

surrsysuni

∆S uni = ∆S sys + ∆S surr ↓

∆S uni > 0 -Freezing at 263K - Spontaneous

9 10 H2O (l) → H2O(s) H2O (l) → H2O(s)

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

H2O (l) → H2O(s) ∆Hf

0 - 286 - 292 S0 + 70 + 48

Freezing at 298K (25C) Freezing at 263K (-10C)

Rxn Temp dependent Spontaneous at Low ↓ temp

120

298

)6000(

JKS

S

T

HS

surr

surr

surr