lecture 01_12_10

lecture 01_12_10 - 1 01-12-10 Today Hess Law Calculating...

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Unformatted text preview: 1 01-12-10 Today Hess Law Calculating with Enthalpies (7-7) Fossil Fuels (7-9) Chapter 12: Van De Waals Forces (12-5/6) Properties of Liquids and Solids (12-1/2/3) Phase Changes and Enthalpies (12-1/2/3) Thursday (01-14-10) Vapor Pressure and Clausius-Clapeyron equation (12-2) Phase Diagrams Structure of Solids (12-7/8) 2 NH 4 SCN + Ba(OH) 2 8H 2 O Ba(SCN) 2 + 2 NH 3 + 10 H 2 O DEMO: Freezing Water DEMO: Eggs - Sunny side up CaO + H 2 O Ca(OH) 2 + heat H<0 + heat H>0 2 The power of thermodynamics: Hess Law B H ? D H (CD) C D H (CD) Enthalpy is a state function; H depends only on final and initial states, not on the path A C H (AC) A C H (AC) A B H (AB) H (DB) D B H (DB) Reaction leading from A to B Reaction A C Reaction C D Reaction D B 3 Example 1 Calculate H f for NO 2 (g). Given: (II) 2 NO (g) + O 2 (g) 2 NO 2 (g) H [II] = -112 kJ (III) N 2 (g) + 2 O 2 (g) 2 NO 2 (g) H [III] = 68 kJ H f [NO 2 ] = 0.5 H [III] = 34 kJ/mol (I) N 2 (g) + O 2 (g) 2 NO (g) H [I] = 180 kJ Example 2 Calculate H f of PCl 3 (l) P 4 (s) + 6 Cl 2 (g) 4 PCl 3 (l) Given: (I) P 4 (s) + 10 Cl 2 (g) 4 PCl 5 (l); H(I) = -1774.0 kJ (II) PCl 3 (l) + Cl 2 (g) PCl 5 (l); H(II) = -123.8 kJ Want to rearrange rxns I & II to sum up to the above reaction. 4 I P 4 (s) + 10 Cl 2 (g) 4 PCl 5 (l) H o = -1774.0 kJ-4II 4 PCl 5 (l) 4 PCl 3 (l) + 4 Cl 2 (g) 4 H o = 4(+123.8) kJ 6 P 4 (s) + 6 Cl 2 (g) 4 PCl 3 (l) H o = -1278.8kJ H f o (PCl 3 ) = -1278.8kJ = -319.7kJ/mol 4 Aeolipile - 1 st century A.D. by Hero of Alexandria http://en.wikipedia.org/wiki/Steam_engine 150 years of Fossil Fuel based Energy Double Acting Stationary Steam Engine Four-Stroke Combustion Engine C + O C + O 2 (air) (air) CO CO 2 2 + heat + heat H = = -394.4 kJ/mol 394.4 kJ/mol CH CH 4 + 2 O + 2 O 2 (air) (air) 2 H 2 H 2 O + CO O + CO 2 2 + heat + heat H =- 890.4 kJ/mol 890.4 kJ/mol Natural Gas/ Oil: Natural Gas/ Oil: Coal: Coal: 5 Example Family Energy Budget (1,725 Mio Btus) Electricity = 51 million Btus Natural gas = 99 million Btus Automobiles = 161 million Btus Air travel = 79 million Btus This all equals 390 million Btus the rest is embodied in purchases and in all the energy it takes to run a society Where do I use Energy?...
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This note was uploaded on 02/16/2010 for the course CHEM 35991 taught by Professor Osterloh during the Spring '10 term at UC Davis.

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lecture 01_12_10 - 1 01-12-10 Today Hess Law Calculating...

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