L23S10_Thermochem,+Enthalpy+03-15-10

L23S10_Thermochem,+Enthalpy+03-15-10 - Chem 1A...

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Unformatted text preview: Chem 1A L23: "Thermochemistry, Enthalpy" Lab 7: Solubility and Spontaneity Goal: Determine the solubility Determine for product, product, Ksp, for Borax. Create a Van t Hoff plot to determine Hº, º, Sº, and Gº Tools and Skills: Titrations © 2004 M. Kubinec, A. Pines L23-1 First Law of Thermodynamics First w:work + System (you can’t win) ( you E=q+w Work for Gases Pext = F/A Summary Euniv = Esys + w=-F h- h = - Pext 3 V Conservation of E Conservation E is a state function 3 E = 2 nRT nRT Expansion Compression - + q:heat Esurr = 0 L22-4 © A.Pines, M.Kubinec,UCB V>O w<O V<O w>O L29-6 Surroundings © A.Pines, M.Kubinec,UCB I sothermal Isothermal Expansion/Compression Expansion/Compression Pext = F/A Adiabatic Adiabatic Expansion/Compression Expansion/Compression Pext = F/A Const T : Const h- E= H=0 h- q=0: E=w q + ww 0 =- = Expansion wq+ Compression w+ qL22-12 © A.Pines, M.Kubinec,UCB Expansion w<O E<O Compression w>O E>O © A.Pines, M.Kubinec,UCB © 2004 M. Kubinec, A. Pines L23-2 L22-14 ChemQuiz© 22.4 A stretched rubber band is suddenly band is suddenly released. What released. What happens to to the temperature of temperature the the rubber band ? A) A) Increases © 2004 M. Kubinec, A. Pines B) Same B) C) Decreases C) L23-3 © 2004 M. Kubinec, A. Pines 1 Chem 1A L23: "Thermochemistry, Enthalpy" Summary Standard Enthalpy Change Reactants Hfº(R) Elements in Elements Standard States Standard Hº = © A.Pines,M.Kubinec,UCB Products Hfº(P) H fº 0 Hfº(P)  Hfº(R) L19-8 © 2004 M. Kubinec, A. Pines L23-5 Thermochemistry aA+bB q= H cC+dD H>0 System Endothermic: q > 0 E System q+ Surroundings © 2004 M. Kubinec, A. Pines Heat is absorbed L23-6 Thermochemistry aA+bB q= H cC+dD H>0 H<0 System Endothermic: q > 0 E System Exothermic: q < 0 qSurroundings © 2004 M. Kubinec, A. Pines Heat is absorbed Heat is released Standard States: Hº 1M, 1atm, 298.15 K L23-7 © 2004 M. Kubinec, A. Pines 2 Chem 1A L23: "Thermochemistry, Enthalpy" ChemQuiz© 23.1 Hº for the reaction (l) H2O (g) (g) H2O (l) -1. Which is is +44 kJ mol Which most hazardous at 100ºC ? at 100 A) A) Water B) Steam C) Water/Steam B) C) © 2004 M. Kubinec, A. Pines L23-8 ChemQuiz© 23.2 H C C C OH HH H Propanol HH H Hº HCCCH HH H Isopropanol H HOH The isomerization of propanol The isomerization of propanol is endothermic. Which endothermic. Which burns cooler? cooler? A) A) Propanol B) Isopropanol C) Same B) C) © 2004 M. Kubinec, A. Pines L23-10 Standard Standard Enthalpy of Enthalpy Formation Formation Compounds Hill Elements Elements in Standard Standard States H 0 Compounds © 2004 M. Kubinec, A. Pines L23-12 © 2004 M. Kubinec, A. Pines 3 Chem 1A L23: "Thermochemistry, Enthalpy" Standard Enthalpy Change Reactants Hfº(R) Elements Elements in Standard Standard States Hº = © 2004 M. Kubinec, A. Pines Products Hfº(P) H 0 Hfº(P)  Hfº(R) L23-13 Standard Standard Enthalpies of Formation Formation (kJ mol-1) H2(g) O2(g) (g) C(s) Al(s) Fe(s) Fe(s) N2(g) 0 +218 +249 +473 C(g) CO2(g) H20(l) H20(g) +717 -394 -286 -242 CH3CH2OH OH (l) (l) -278 -1274 -824 -1676 L23-14 H(g) O(g) N(g) C6H12O6 (s (s) Fe2O3 (s) (s) Al2O3 (s) (s) © 2004 M. Kubinec, A. Pines ChemQuiz© 23.3 What What is Hº (kJ mol-1) for for the oxidation of Fe ? oxidation Fe (s) Fe (s) + O2 (g) (g) Fe2O3 (s) Fe because Fe & O2 are zero LO2 A) A) -575 © 2004 M. Kubinec, A. Pines B) -824 B) C) -1073 C) L23-15 © 2004 M. Kubinec, A. Pines 4 Chem 1A L23: "Thermochemistry, Enthalpy" ChemQuiz© 23.4 Which Which of the following to will react with Fe2O3 to produce molten Fe? Fe? A) A) C (s) B) Fe (s) Fe C) Al (s) Al © 2004 M. Kubinec, A. Pines L23-17 Lecture Complete © 2004 M. Kubinec, A. Pines L23-19 © 2004 M. Kubinec, A. Pines 5 ...
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