CHEM 113 1st Edition Lecture 14 Outline of Last Lecture I. Solving Equilibrium ProblemsII. Practice ProblemOutline of Current Lecture  Le Chatelier’s Principle The Effect of Concentration The Effect of Pressure The Effect of Temperature The Effect of CataylystsCurrent LectureFactors Affecting Equilibrium- Le Chatelier’s Principleo When a chemical system at equilibrium is disturbed, it retains equilibrium by undergoing a net reaction that reduces the effect of the disturbance A system is disturbed when a change in conditions forces it temporarily out of equilibrium The system responds to a disturbance by a shift in the equilibrium position A shift to the left is a net reaction from product to reactant A shift to the right is a net reaction from reactant to product- The Effect of a Change in Concentrationo If the concentration of A increases, the system reacts to consume some of it If a reactant is added, the equilibrium position shifts to the right If a product is added, the equilibrium position shifts to the lefto If the concentration of B decreases, the system reacts to consume some of it If a reactant is removed, the equilibrium shifts to the rightThese 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. If a product is removed, the equilibrium shifts to the righto Only substances that appear in the expression for Q can have an effect Meaning that if it is a heterogeneous equilibrium, pure solids and liquids do not have an effect.o A change in concentration has no effect on the value of Ko Figures 17.7 & 17.8 both visually represent these concepts- The Effect of a Change in Pressure (volume)o Changes in pressure effect equilibrium systems containing gaseous components Changing the concentration of gaseous component causes the equilibrium to shift accordingly Adding an inert gas has no effect on the equilibrium position, as long as the volume does not changeo Changes in pressure due to a change in volume has no effect on the value of Ko Figure 17.9 shows the effect of pressure on systems - The Effect of a Change in Temperatureo To determine the effect of a change in temperature on equilibrium, heat is considered a component of the system Heat is a product in an exothermic reaction Heat is a reactant in an endothermic reactiono An increase in temperature adds heat, which favors the endothermic reactiono A decrease in temperature removes heat, which favors the exothermic reactiono Temperature and K The only factor that affects the value of K for a given equilibrium system istemperature For an endothermic reaction, an increase in temperature will cause K to increase For an exothermic reaction, an increase in temperature will cause K to decrease These relationships are shown in the following van’t Hoff equation *Notice how it is similar to form of the Arrhenius equation- Catalysts and Equilibriumo Catalysts have no effect on the equilibrium positiono They simply speed up reactions by lowering its activation energy, therefore it speeds up the forward and reverse reactions to the same extentTable 17.4 sums up all of these variables and how they effect equilibrium and