1.Video Tutorial on Gibbs Free Energy,Entropy, Second Law ofThermodynamics and Spontaneity. Prepared by Lawrence Kok http://lawrencekok.blogspot.com

2. Video on Entropy and Free EnergyEntropy from Khan Academy Entropy calculation from Khan Academy Video on Gibbs Free Energy Entropy explained using microstates 3. Entropy, Free Energy and SpontaneityEntropy Measures the degree of DISORDER for a system Measures the probability or chance for a system, both in distribution of particles in spaceand distribution of energy How will a reaction go ? Why gas MIXES and NOT UNMIX ? Why concentrated solute DIFFUSE and NOT UNDIFFUSE? 4. Entropy and SpontaneityImportant concepts for Entropy Unit for entropy JK-1mol-1 Formula for entropy, S = k ln W k = Boltzmann constantW = Number ways a particle can arrange in space Absolute entropy can be measured! Entropy of a perfectly order solid crystal at OK is ZERO Entropy of an element under standard condition is NOT ZEROS (H2) gas = 130.6JK-1mol-1 Standard entropy change, S = Entropy change per mole of a substanceheated from OK to standard Temp of 298K 5. Entropy and SpontaneityENTROPY CHANGE, S Change in the disorder of a system Higher disorder Higher entropy Change in state from SOLID LIQUID GAS Higher entropy Greater number of particles formed in products Higher entropy Complex molecules (more atoms bonded) Higher entropy Higher temperature Particles vibrate faster More random Higher entropy Standard entropy, S /298K S / JK-1mol-1 6. Second Law of Thermodynamics For all spontaneous reactions, TOTAL entropy of the universe Suni always INCREASES Formula for Ssys = S (products) - S (reactants) Formula for S(surrounding) Reaction will likely to happen if - Conclusion : For spontaneous reaction, Suni must > O (positive) 7. Gibbs Free Energy, G To predict if a reaction will likely to happen Hsys = -ve (exothermic) Ssys = +ve (entropy increses ) ssurr = +ve (entropy increases ) Suni = +ve (entropy increases ) Suni = Ssys + Ssurr > 0, (+ve) positive Gsys =Hsys TSsys < 0, (-ve) negativeGibbs Free Energy, G is used G is used or preferred because it involves the system while S involves system and surrounding Easier to determine H and S for a system G = H -TSUnit for Gsys = kJmol-1 Hsys = kJmol-1 Ssys = JK-1mol-1 8. Combination Hsys , Ssys and Gsys to predict if reaction is spontaneous 9. Combination Hsys , Ssys and Gsys to predict if reaction is spontaneous Hsys -ve Ssys +ve Always Spontaneous Hsys +ve Ssys ve Non Spontaneous Hsys +veSsys +ve Spontaneous if Temp High Hsys -veSsys ve Spontaneous if Temp low 10. Combination H, S and G to predict if reaction is spontaneous at 298K SsysSsurrSsys = Ssys (product) Ssys (reactant) Ssurr = - Hsys /T = (70.0) (188.7)+= -(-44100)/298 = -118.7 JK-1mol-1 = +148.0JK-1mol-1 Suni = Ssys + Ssurr = (-118.7) + 148.0 = +29.3 JK-1mol-1 11. Combination H, S and G to predict if reaction is spontaneous at 298K SsysSsurrSsys = Ssys (product) Ssys (reactant) Ssurr = - Hsys /T = (70.0) (188.7)+= -(-44100)/298 = -118.7 JK-1mol-1 = +148.0JK-1mol-1 Suni = Ssys + Ssurr = (-118.7) + 148.0 = +29.3 JK-1mol-1 AND G = H -TS= (-44.1) (298 x -118.7/1000) = - 8.72kJmol-1Conclusion : Spontaneous - Entropy of system Ssys DECREASES BUT heat released to the surroundingINCREASES the entropy of surrounding, Ssurr Spontaneous - G = -ve 12. Combination H, S and G to predict if reaction is spontaneous at 298K SsysSsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (213.6 + 2x171) (186.0 + 2x205)+= -(-890000)/298 = -40.4 JK-1mol-1 = +2986.5JK-1mol-1Suni = Ssys + Ssurr = -40.4 + 2986.5= +2946 JK-1mol-1 13. Combination H, S and G to predict if reaction is spontaneous at 298K Ssys SsurrSsys = Ssys (product) Ssys (reactant) Ssurr = -Hsys /T = (213.6 + 2x171) (186.0 + 2x205)+ = -(-890000)/298 = -40.4 JK-1mol-1= +2986.5JK-1mol-1Suni = Ssys + Ssurr = -40.4 + 2986.5= +2946 JK-1mol-1 ANDG = H -TS = (-890) (298 x -40.4/1000)= - 878 kJmol-1Conclusion : Spontaneous - Entropy of system Ssys DECREASES BUT heat released to the surroundingINCREASES the entropy of surrounding, Ssurr Spontaneous - G = -ve 14. Combination H, S and G to predict if reaction is spontaneous at 298KSsys SsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (2 x 115) (130.6)+= -(+436000)/298 = +99.4 JK-1mol-1 = -1463 JK-1mol-1Suni = Ssys + Ssurr = +99.4 + (-1463)= -1363.6 JK-1mol-1 15. Combination H, S and G to predict if reaction is spontaneous at 298KSsysSsurrSsys = Ssys (product) Ssys (reactant) Ssurr = -Hsys /T = (2 x 115) (130.6)+ = -(+436000)/298 = +99.4 JK-1mol-1= -1463 JK-1mol-1Suni = Ssys + Ssurr = +99.4 + (-1463)= -1363.6 JK-1mol-1ANDG = H -TS = (436) (298 x 99.4/1000)= +406 kJmol-1Conclusion : Non Spontaneous - Entropy of system Ssys INCREASES BUT heat absorbed from surroundingDECREASES the entropy of surrounding, S surr NON spontaneous - G = +ve 16. Combination H, S and G to predict if reaction is spontaneous at 298K Is it possible to freeze water at 298K ( 25oC)At 25oCSsys SsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (48) (70) + = -(-6010)/298 = -22 JK-1mol-1 = +2016 JK-1mol-1 Suni = Ssys + Ssurr= -22 + (+2016) = -1.84 JK-1mol-1 17. Combination H, S and G to predict if reaction is spontaneous at 298K Is it possible to freeze water at 298K ( 25oC)At 25oCSsys SsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (48) (70) + = -(-6010)/298 = -22 JK-1mol-1 = +2016 JK-1mol-1 Suni = Ssys + Ssurr= -22 + (+2016) = -1.84 JK-1mol-1ANDG = H -TS = (-6.01) (298 x -22/1000)= +0.54 kJmol-1Conclusion : Non Spontaneous - Entropy of system Ssys DECREASES more than > theINCREASE in entropy of surr, Ssurr due to heat released to the surrounding NON spontaneous - G = +ve 18. Combination H, S and G to predict if reaction is spontaneous at 263K Is it possible to freeze water at 263K ( -10oC)At -10oCSsys SsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (48) (70)+ = -(-6010)/263 = -22 JK-1mol-1= +22.85 JK-1mol-1Suni = Ssys + Ssurr = -22 + (+22.85)= +0.85 JK-1mol-1 19. Combination H, S and G to predict if reaction is spontaneous at 263K Is it possible to freeze water at 263K ( -10oC)At -10oCSsys SsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (48) (70)+ = -(-6010)/263 = -22 JK-1mol-1= +22.85 JK-1mol-1Suni = Ssys + Ssurr = -22 + (+22.85)= +0.85 JK-1mol-1AND G = H -TS= (-6.01) (263 x -22/1000) = -0.23 kJmol-1Conclusion : Spontaneous - Entropy of system Ssys DECREASES BUT heat released to surroundingINCREASES the entropy of surrounding, Ssurr Spontaneous - G = -ve 20. Combination H, S and G to predict if reaction is spontaneous at 298K Is it possible to decompose CaCO3 (s) CaO (s) + CO2 (g) At 25oCSsysSsurrSsys = Ssys (product) Ssys (reactant) Ssurr = -Hsys /T = (39.7 + 213.6) (92.9) += -(+178300)/298 = + 160.4 JK-1mol-1= - 598.3 JK-1mol-1Suni = Ssys + Ssurr= +160.4 + (- 598.3)= - 438 JK-1mol-1 21. Combination H, S and G to predict if reaction is spontaneous at 298K Is it possible to decompose CaCO3 (s) CaO (s) + CO2 (g) At 25oCSsysSsurrSsys = Ssys (product) Ssys (reactant) Ssurr = -Hsys /T = (39.7 + 213.6) (92.9) += -(+178300)/298 = + 160.4 JK-1mol-1= - 598.3 JK-1mol-1Suni = Ssys + Ssurr= +160.4 + (- 598.3)= - 438 JK-1mol-1AND G = H -TS= (+ 178.3) (298 x +160.4/1000) = + 130.5 kJmol-1Conclusion : Non Spontaneous - Entropy of system Ssys INCREASES BUT heat absorbed from surroundingDECREASES the entropy of surrounding, Ssurr NON spontaneous- G = +ve 22. Combination H, S and G to predict if reaction is spontaneous at 1500K Is it possible to decompose CaCO3 (s) CaO (s) + CO2 (g)At 1227oCSsysSsurrSsys = Ssys (product) Ssys (reactant) Ssurr = -Hsys /T = (39.7 + 213.6) (92.9) += -(+178300)/1500 = + 160.4 JK-1mol-1= - 118.8 JK-1mol-1 Suni = Ssys + Ssurr= +160.4 + (- 118.8) = + 41.6 JK-1mol-1 23. Combination H, S and G to predict if reaction is spontaneous at 1500K Is it possible to decompose CaCO3 (s) CaO (s) + CO2 (g)At 1227oCSsysSsurrSsys = Ssys (product) Ssys (reactant) Ssurr = -Hsys /T = (39.7 + 213.6) (92.9) += -(+178300)/1500 = + 160.4 JK-1mol-1= - 118.8 JK-1mol-1 Suni = Ssys + Ssurr= +160.4 + (- 118.8) = + 41.6 JK-1mol-1ANDG = H -TS = (+ 178.3) (1500 x +160.4/1000)= - 62.3 kJmol-1 Conclusion : Spontaneous - Entropy of system Ssys INCREASES more than > DECREASES in entropy of surr, Ssurr due to heat absorbed from surrounding Spontaneous - G = -ve 24. Combination H, S and G to predict if reaction is spontaneous at 298KIs the reaction possible 2NO (g) + O2 (g) 2NO2 (g) Ssys SsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (2 x 240) (2 x 210.7+102.5) + = -(-114000)/298 = - 43.9 JK-1mol-1= +382.5 JK-1mol-1 Suni = Ssys + Ssurr= -43.9 + (+382.5) = +339 JK-1mol-1 25. Combination H, S and G to predict if reaction is spontaneous at 298KIs the reaction possible 2NO (g) + O2 (g) 2NO2 (g) Ssys SsurrSsys = Ssys (product) Ssys (reactant)Ssurr = -Hsys /T = (2 x 240) (2 x 210.7+102.5) + = -(-114000)/298 = - 43.9 JK-1mol-1= +382.5 JK-1mol-1 Suni = Ssys + Ssurr= -43.9 + (+382.5) = +339 JK-1mol-1 ANDG = H -TS = (- 114) (298 x -43.9/1000)= -100.9 kJmol-1Conclusion : Spontaneous - Entropy of system Ssys DECREASES less than