Chem_Sheet_2_3 - Spontaneous: G is negative Non...

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Spontaneous : ΔG is negative Non spontaneous : ΔG is positive At equilibrium: ΔG = 0 Entropy (S) : thermodynamic property related to the way in which the energy of a system is distributed among the available energy levels. The greater the number of configurations of the microscopic particles among the energy levels in a system, the greater the entropy of the system ΔS = q rev / T (q = heat) ΔS o = entropy of one mole of a substance in its standard state (25 o C or 298.15 K) ΔS = Σv p S o (products) - Σv p S o (reactants) works with ΔG and ΔH as well G = H – TS ΔG = ΔH - T ΔS ΔG = ΔG o + RT lnQ ΔG o = ΔH o - T ΔS o ΔG o = -RT lnK eq ΔG = RT ln(Q/K eq ) R = 8.3145 J/mol K ΔS o vapn = ΔH o vapn / T bp ln (K 2 / K 1 ) = (ΔH o / R)(1 / T 1 – 1 / T 2 ) can be used with partial pressures and moles Exothermic- heat is a product (ΔH is negative) Endothermic- heat is a reactant (ΔH is positive) aA + bB… cC + dD Rate = Rate = k[A] m [B] n units of k = M (1-overall order) S -1 [Reaction], int Initial Rate Reaction Order doubles first quadruples second Increases eightfold third unchanged zero Activation energy (E a ) : the minimum energy that must be supplied by collision in order for a reaction to occur ΔH = E a (forward) – E a (reverse) k=Ae -Ea/RT ln k = -E a / RT + lnA ln (K 2 / K 1 ) = (E a / R)(1 / T 1 – 1 / T 2 ) In a reaction mechanism, the rate determining step is the slow step and the stoichiometric coefficients in the step are the order When a fast equilibrium is before a slow step, the equilibrium constant can be substituted into the slow step, producing a rate law A catalyst increases the reaction rate without itself being changed in a chemical reaction An inhibitor is a substance that makes an enzyme either less active or completely inactive Oxidation: loss of electrons. Oxidizing agent accepts electron. Oxidation number increases Reduction: gain in electrons. Reducing agent donates electrons. Oxidation number decreases
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This note was uploaded on 04/08/2008 for the course CHEM 11b taught by Professor Petsko during the Spring '07 term at Brandeis.

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Chem_Sheet_2_3 - Spontaneous: G is negative Non...

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