CHEM 102 1nd Edition Lecture 7 Outline of Last Lecture I. TerminologyII. Joule and CalorieIII. Specific heatIV. Heat of fusionV. Heat of vaporizationOutline of Current Lecture VI. ExampleVII. Gibbs Free Energy, GVIII. Delta G reaction indicates spontaneity IX. Gibbs Helmhots equationCurrent Lecture- At 25 degrees C: 3NO (g)  N2O (g) + NO2 (g)o We want to know if this reaction is spontaneous (delta S universe = delta S system + delta S surroundings  Delta S system = (-delta H rxn/T) Delta S system = -172.4 J/Ko Delta S surroundings: 3NO (g)  N2O (g) + NO2 (g) Delta Hf: 90.25 82.05 33.2 Delta H rxn: (82.05 + 33.2) – 3(90.2) = -155 kJ Delta S surroundings: -(-155 kJ)/298.15 = 0.5125 kJ/Ko Delta S universe = -172.4 J/K + 5215 J/K = 349.1 J/K- Gibbs Free Energy, Go G: thermodynamic state function State function indicates amount of energy available for a system to do useful worko Delta G: maximum amount of useful work that can be done by reaction at constant T,P state function (kJ/mol) Delta G calculate from delta Gf 298 (in tables)- Delta Gf = 0- Delta Hf = 0- Delta Sf does not equal zero for elements in standard state These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Delta G reaction indicates spontaneity o Delta G < 0forward reaction spontaneous o Delta G > 0forward reaction is NOT spontaneous but reverse reaction IS spontaneous o Delta G = 0  reaction is at equilibrium Reactantsproducts just as fast as productsreactants- 3NO (g)  N2O (g) + NO2 (g)86.54 104.2 51.3o Delta G reaction = (104.2+51.3) – 3(86.54) = -104 kJo Negative so reaction is spontaneous at 25 degrees C (because data in table is at 25 degrees C)- Gibs Helmhots equationo Delta G reaction = delta H reaction – T(delta S reaction)o For 3NO (g)  N2O (g) + NO2 (g) Delta G reaction = delta H reaction – T(delta S reaction) Delta G reaction = 755 kJ – (298.15 K)(-0.1724 kJ/K) = -104.1