CHEM 001B Lecture Notes - Lecture 24: Spontaneous Process, Isothermal Process, Joule
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Q rev = flow of heat for reversible process. A process that can be run in the reverse direction in such a way that, once the system has been restored to its original state, no net energy has flowed either to the system or to its surroundings. Consider an ice cube melting at 0. 0 (273 k) on a countertop at 22. 0 (295 k). It takes 6. 01 kj of energy to melt 1 mole of ice. Heat flows into ice cube: s sys = q rev /273 k = 22. 0 j/k. Heat flows out of countertop: s sys = -q rev /295 k = -20. 4 j/k. S univ = (q rev /273) + (-q rev /295) > 0. N = coefficients of the products/ reactants in the balanced equation. Using values from appendix 4, calculate the standard entropy change for the. S rxn = [(4)(213. 8) + (6)(69. 9)] - [(7)(205. 0) + (2)(229. 5)] S rxn = [(855. 2) + (419. 4)] -[(1435) + (459)]
