# lec12 - Last Time Dynamic Equilibrium Equilibrium constant...

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Last Time • Dynamic Equilibrium • Equilibrium constant – Concentration – K c – Pressure – K p • Hess “like” law Recall – Equilibria • Homogeneous mixtures – gases aA + bB cC + dD K c = • Heterogeneous mixtures – drop solid in K c [A] a [B] b [C] c [D] d P C c P D d P A a P B b (RT) Δ n = (RT) Δ n K p = Non-equilibrium Conditions •K c and K p only good at equilibrium • Reaction quotient – Mathematically the same as K’s except non– equilibrium parameters are used –Q c like K c – all in mol/L –Q p like K p – all in atm … same relation to Q c • Q predicts reaction direction – Q < K forward : Q > K reverse Example Last time we calculated the equilibrium constant for the reaction of hydrogen with iodine gas to form HI(g) to be K c = 48.9. A student measures the concentrations at a given time during the reaction to be [H 2 ] = 2.8x10 –2 mol/L, [I 2 ] = 8.9x10 –3 mol/L, and [HI] = 1.45x10 –3 mol/L. Which way does the reaction go to achieve

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## This note was uploaded on 04/23/2008 for the course CHEM 2B taught by Professor Clemens during the Winter '08 term at UC Davis.

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lec12 - Last Time Dynamic Equilibrium Equilibrium constant...

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