DynamicEquilibrium-NUIGalwayNationalUniversityofIreland动态平衡高威的爱尔兰国立大学

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Dynamic EquilibriumChapter 15,Example,liquid+heat,vapour,an endothermic physical change,Le Chateliers Principle,When a dynamic equilibrium is upset by a disturbance,the system responds in a,direction,that tends to counteract the disturbance and,if possible,restore equilibrium,liquid+,heat,vapour,Increase the temperature(add heat),Le Chateliers Principle,When a dynamic equilibrium is upset by a disturbance,the system responds in a,direction,that tends to counteract the disturbance and,if possible,restore equilibrium,liquid,+heat,vapour,Liquid evapourates to absorb the added heat and the,position of the equilibrium shifts to the right,Chemical Equilibrium,CH,3,COOH+H,2,O,H,3,O,+,+CH,3,COO,-,For a given composition of a system,equilibrium is independent of which side you approach it from.reactions are,REVERSIBLE,N,2,O,4,(g),2NO,2,(g),C,init,0.0350 mol0,or00.0700 mol,C,equil,0.0292 mol0.0116 mol,Equilibrium Law,simple relationship between molar concentrations(or pressures)of reactants and products at equilibrium,H,2,(g)+I,2,(g),2HI(g)(at 440C),Mass action expression:,Where Q is the reaction quotient,LAW:at equilibrium the reaction quotient is equal to the equilibrium constant,K.,In general for,dD+eE,gG+hH,Heterogeneous Equilibria,(involving more than one phase),Equilibrium Law for Gaseous Reactions,For gaseous reactions use partial pressures,P,to give an equilibrium constant(K,p,),The Magnitude of Equilibrium Constants,The equilibrium constant,K,is the ratio of products to reactants.,Therefore,the larger,K,the more,products are present at equilibrium.,Conversely,the smaller,K,the more,reactants are present at equilibrium.,If,K,1,then products dominate,at equilibrium and equilibrium lies,to the right.,If,K,increase P,System opposes this by reducing the number of molecules,Predicting direction of equilibrium changes(Le Chatelier redux),Changing temperature,(heat),System opposes this by trying to absorb the added heat,ONLY factor that actually changes the value of K,Effect of catalyst,Speeds up approach to equilibrium,but does not,alter K or the system(kinetics),