BCHM 425 Lecture Notes - Lecture 3: Peptide, Catabolism, Lactate Dehydrogenase
28 Sep 2016
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The following expressions have been used to establish criteria for spontaneous change: deltas-isolated system> 0 and deltag < o. Discuss the origin, significance, and applicability of each criterion. Molecular basis interpretation between the second and third law. Process spontaneity occurs even if entropy change of system is itself negative. Example: binding of oxidized nad+, an electron carrier, to lactate dehydrogenase. Its" rxn delta s is -16. 8 j/k: negative sign expected since association of 2 reactants give rise to a more compact system. Results in more organized structure but is still spontaneous. Paradox seen here considering entropy of both the system and its surroundings is essential for determining whether or not its spontaneous or not. The 16. 8 j/k refers to the entropy change of the system, not the whole universe. To apply the second law, the total entropy would be calculated to sum the changes both in system and surroundings.
