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Unformatted text preview: Fall 20 10 CH301 Worksheet 1 1 Answer Key: Thermodynamic Calculations for Chemical Reactions and Phase Changes Check for explanation of solution key at bottom of pageAssume T = 298K. First describe the reaction below where it is written, then predict the sign for each answer and only then, do the calculation. The BE values are at the bottom of the worksheet. The formation constants are found in the textbook appendix and also as Worksheet 1 1a. This worksheet is painful at first, but once you get it you are a profoundly better chemist (and exam 3 test taker.) Chemical Reaction H (kJ) BE (kJ) n gas w (kJ)= - nRT n system S (kJ) G (kJ) CH 4 g + 2O 2 g CO 2 g + 2H 2 Og Combustion reaction, would predict large heat and spontaneous reaction. n = 0 means no work, small entropy change. -802 -802 0 0 0 -1 -801 2H 2 g + O 2 g 2H 2 Og Spontaneous combustion reaction, would predict large heat. n = negative which means entropy decreases -484 -482 - 1 +2.5 -1 -27 -458 C 2 H 5 OH l + 3O 2 g 2CO 2 g + 3H 2 Og Spontaneous combustion reaction, would predict large heat. n = is positive so work on surroundings and positive entropy....
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This note was uploaded on 10/10/2011 for the course CH 50995 taught by Professor Laude during the Fall '10 term at University of Texas at Austin.
- Fall '10