Chem 102 1st Edition Lecture 6Outline of Last Lecture I. Chemical EquilibriumA. Dynamic Equilibrium B. Equilibrium ConstantsOutline of Current Lecture I. Equilibrium ConstantA. PressureB. MagnitudeC. CalculatingD. Predicting Direction E. Microscopic ReversibilityII. Le Chatelier’s PrincipleA. Volume and PressureB. TemperatureC. CatalystsCurrent LectureI. Equilibrium constantA. Pressure:-Kp is the equilibrium constant for reactions involving gases.Kp is based on partialpressures measured in atm. SO:PA = [A](RT)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.B. Magnitude- The equilibrium constant K, is the ratio of products to reactants. Therefore, the larger the K the more products present at equilibrium. K>1 products are dominate, if K<1 reactants are dominant. C. Calculating Equilibrium Constants- First tabulate initial(usually 0) and equilibrium concentrations or partial pressures, if they are given for a species, calculate the change. Then use stoichiometry on the change in concentration line only to calculate changes inconcentration for all species. Deduce the equilibrium concentrations of all species. D. Predicting Direction- Find Q and if it is greater than K than the reverse reaction must occur to reach equilibrium, but if Q is less than K than the forward reaction must occur. E. Microscopic Reversibility- The forward and its reverse reaction must have thesame activated complex or transition state. II. Le Chatelier’s Principle- If a system at equilibrium is disturbed, the system will move in such a way as to counteract the disturbance. Adding a reactant or a product shifts the equilibrium away from the increase, removing shifts the equilibrium towards thedecrease. To optimize the amount of product at equilibrium, we need to flood the vesselwith reactant and continuously remove product. A. Volume and Pressure- As volume decreases pressure increases. If pressure increases the system will shift to remove gases and decrease pressure, counteracting theincrease. An increase in pressure favors the direction that has fewer moles of gas. If the moles are the same than the pressure has no effect. B. Temperature Change- The equilibrium constant is temperature dependent. Endothermic reaction change in H is positive while exothermic is negative. Adding heat favors away from the increase. Removing heat favors the direction of the increase. C. Catalysts- These lower the activation energy barrier for the reaction. Meaning, a catalyst decreases the time for a reaction to reach equilibrium. Catalysts do not effect the composition of the equilibrium
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