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Class 35 Monday April 19 Today s Coverage 19 8 19 9 K Q and G Helpful items for today Equations sheet located on Canvas Pencil pen and paper or tablet Reef open and ready to go Calculator Activity 4 pH of Acids Mastering 7 Chp 17B 19B Due Friday 4 23 at 10 pm MT Due Monday 4 19 at 10 pm MT Recall last Wed Polyprotic acids From K to G Next Lewis acids Recall G u st relate m G d K a n Reaction Spontaneity Direction Go RT ln K Locate on Equations Sheet R 8 31 J K mol T Kelvin Which of the following is true a K 1 G rxn is positive b K 1 G rxn is negative c G rxn 0 at equilibrium d None of the above are true Answer D Go RT ln K Locate on Equations Sheet What is the value of G rxn given an equilibrium constant of 1 32 103 at 250C a 1 49 kJ b 1 49 kJ c 17 8 kJ d 17 8 kJ e 7 73 kJ Answer C Go RT ln K Locate on Equations Sheet At 298 K G rxn 12 3 kJ for the reaction A B Does the reaction favor the formation of reactants or products a Reactants because K 1 b Reactants because K 1 c Products because K 1 d Products because K 1 e Neither products nor reactants because K 1 Answer B Go RT ln K Locate on Equations Sheet Now that we have a solid framework for aqueous EQ consider the following Some water is spilled on the floor From experience will it evaporate Predict from the sign of G What s going on Standard state 1 atm vs non standard state 1 atm Kp 0 0313 Need new G equation H2O l H2O g G 8 59 kJ mol G Go RT ln Q G RT lnK RT lnQ G RT ln Keq R 8 31 J K mol T Kelvin Q K Q K Q K G 0 G 0 G 0 spontaneous forward at equilibrium spontaneous reverse Any Starting Condition NOT at equilibrium Q K At Standard State At Equilibrium Q 1 Q K Q K G G RT ln Q G RT ln K G 0 Standard Conditions PH2O 1 atm G G RT ln Q Q K 8 59 kJ mol RT ln 1 8 59 kJ mol Nonstandard Conditions PH2O dry nonhumid day 5 00 x 10 3 atm Q 5 00 x 10 3 atm G G RT ln Q Q K 8 59 kJ mol 8 314 J mol K 298 K ln 5 00 x 10 3 8 59 kJ mol 13 1 kJ mol 4 5 kJ mol Equilibrium Conditions PH2O 0 0313 atm G G RT ln Q Q K 8 59 kJ mol 8 314 J mol K 298 K ln 0 0313 8 59 kJ mol 8 39 kJ mol 0 H2O l H2O g G 8 59 kJ mol Standard Conditions PH2O 1 atm G G RT ln Q Q K 8 59 kJ mol RT ln 1 8 59 kJ mol Nonstandard Conditions PH2O dry nonhumid day 5 00 x 10 3 atm Q 5 00 x 10 3 atm G G RT ln Q Q K 8 59 kJ mol 8 314 J mol K 298 K ln 5 00 x 10 3 8 59 kJ mol 13 1 kJ mol 4 5 kJ mol Equilibrium Conditions PH2O 0 0313 atm G G RT ln Q Q K 8 59 kJ mol 8 314 J mol K 298 K ln 0 0313 8 59 kJ mol 8 39 kJ mol 0 H2O l H2O g G 8 59 kJ mol Which of the following is true a K 1 G rxn is positive b K 1 G rxn is negative c G rxn 0 at equilibrium d Grxn 0 at equilibrium e None of the above are true Answer D Calculate G at 298 K for the reaction below 2 NO g O2 g 2 NO2 g Go 71 2 kJ A 71 2 kJ B 4000 kJ 91 7 kJ C D 50 7 kJ But First Strategy from what is given A Any starting B At standard state C At equilibrium Calculate G at 298 K for the reaction below 2 NO g O2 g 2 NO2 g Go 71 2 kJ Q PNO2 2 PNO 2 PO2 Q 2 00 2 0 100 2 0 100 4 00 103 G Go RT ln Q G 7 12 104 J 8 314 J K mol 298 K ln 4 00 103 G 5 07 104 J or 50 7 kJ The G cid 155 for the reaction N2O4 2 NO2 is 4 8 kJ Calculate K for this reaction Check Point Be ready to click with Reef on Wed A 4 8 B 0 021 C 1 94 D 0 14 But First Strategy from what is given A Any starting B At standard state C At equilibrium Temperature Dependence of K G0 RT ln K G0 H0 T S0 RT ln K H0 T S0 y m x b K n L Slope H rxn R Plot of lnK vs 1 T in kelvins gives linear plot with slope Ho R A graph of ln K vs 1 T has a slope of 3052 What is H rxn a 25 4 kJ b 25 4 kJ c 367 J d 367 J e 3052 J Slope H rxn R Check Point Be ready to click with Reef on Wed

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