Chem 104 1st Edition Lecture 35Outline of Last Lecture I. Checking approximationII. Le Chatelier’s PrincipleOutline of Current LectureI. Effects of adding a gasII. Change in volumea. Disturbing volumeb. Effect of volume changing the equilibriumIII. Effect of temperaturea. Effect of catalystCurrent LectureI. Disturbing equilibrium:a. Adding a gas reactant will increase the partial pressure and the equilibrium will shift to the right. This increases the concentration but does not increase the partial pressure of other gases in the mixture. Adding an inert gas to a mixture has no effect on the equilibrium position and does not affect other gases in the reaction.PV =nRTBut converted to solve for a gas:PV = MRTII. Volume change on equilibrium:a. Decreasing the volume of a container increase the concentration of gases and the partial pressure. It does not change the concentration of solutions. Accordingto Chatelier’s Principle, the equilibrium should shift to the side with fewer gas molecules. Overall, increasing the pressure, decreases the volume and vice versa since they move opposite one anotherIII. When working with gases, includes four variables: volume, pressure, number of molecules, and temperature. When a reaction releases heat it will be part of the product.Example: CH4(g)+2O2↔CO2+2H2O, ∆Hrxn= -800 kj/molSo….C H4+2 O2↔ C O2+2 H2O +∆ HThe equilibrium shifts to the left.Overall: endothermic reactions cause the equilibrium to shift to the right; exothermic reactions cause the equilibrium to shift to the left. You cannot solve unless you know if the reaction is endothermic or exothermic.Adding heat to an exothermic reaction will decrease the concentration of products and increase the concentration of reactants. Adding heat to an exothermic reaction will also decrease the equilibrium constant, if endothermic is will increase the equilibrium constant.Catalysts and inert gases have no effect on the
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