ReviewLecture1e_2014

On proceeds towards side with most moles of gas if in

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Unformatted text preview: iLs direc!on away from the species added. • Subtrac!ng a species shiLs direc!on towards the species removed. B. Change in volume • If volume is decreased, the reac!on proceeds towards the side with least moles of gas. • If volume is increased, the reac!on proceeds towards side with most moles of gas. • If in the overall equa!on there are the same numbers of moles of gas on both sides, a volume change will not affect the equilibrium. Le Châtelier’s Principle: Qualita7ve Summary (Yablonsky and Ray, Int. J Chem Reactor Eng. 2008) Endothermic: Exothermic: A + B + heat A+B k1 ⌦ k-1 k1 ⌦ k-1 C C + heat C. Change in pressure • Increase in pressure shiLs equilibrium in direc!on of decrease in the number of moles of gas • Decrease in pressure shiLs equilibrium in direc!on of increase in number of moles of gas. • If in the overall equa!on there are the same numbers of moles of gas on both sides, a pressure change will not affect the equilibrium. D. Change in temperature • If the reac!on is endothermic: • Increase in temperature shiLs equilibrium in the direc!on of increase of product concentra!ons. • If the reac!on is exothermic: • Increase in temperature shiLs equilibrium in the direc!on of increase of reactant concentra!ons. Temperature Effect on Equilibrium Constant Keq = exp ✓ G RT 0 ◆ = exp ✓ S R 0 ◆ exp H RT 0 ◆ K0 5 4 Keq êK0 3 Hrxn < 0 (exothermic) T increasing 2 1 0 0 T increasing 20 Hrxn > 0(endothermic) 40 60 80 100 T°C In exothermic reac!on Equilibrium Constant decreases from above as tem...
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This document was uploaded on 03/14/2014.

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