Chem_2_Final_Sheet

Chem_2_Final_Sheet - 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 Use integrated rate law to relate concentration to time, pressure to time, or mass to time Use experimental data to determine reaction order (to establish differential rate law) Use differential rate law to calculate k Use differential rate law to calculate an instantaneous rate at specidifed reaction concentrations 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 Reduction : a gain in electrons and a decrease in oxidation state. Ag + + e - Ag Oxidation : a loss of electrons and an increase in oxidation state. Cu Cu 2+ + 2e -. How to Balance a Redox Reaction: For half reactions: 1. Balance all non-O, H atoms for mass 2. Balance O (add H 2 O to O-deficient side 3. Balance H (add H + to H-deficient side) 4. Balance charge (add e - to more positive side so that reactant and product charges are equal) 5. Adjust half reactions so e - cancels 6. Add half-reactions and simplify To make a redox reaction acidic, add equal amounts of OH
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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_2_Final_Sheet - Spontaneous G is negative Non...

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