IB Chemistry on Le Chatelier's Principle, Equilibrium Constant Kc and Dynamic Equilibrium

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IB Chemistry on Le Chatelier's Principle, Equilibrium Constant Kc and dynamic Equilibrium

Text of IB Chemistry on Le Chatelier's Principle, Equilibrium Constant Kc and Dynamic Equilibrium

  • 1. Tutorial on Le Chateliers Principle,Equilibrium Law, Position of Equilibriumand Equilibrium Constant . Prepared by Lawrence Kok http://lawrencekok.blogspot.com

2. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established again Effect of Concentration on the position of equilibrium Increase in Conc - position of equilibrium shift to right/left - Conc will be Reduced Decrease in Conc position of equilibrium shift to right/left - Conc will be Increased Fe3+ + SCN- Fe(SCN)+2(yellow)(red Blood)Click to view videoIncrease SCN- or Fe3+ Conc Decrease Fe3+ Conc Decrease SCN- Conc 3. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established againEffect of Concentration on the position of equilibrium Increase in Conc - position of equilibrium shift to right/left - Conc will be Reduced Decrease in Conc position of equilibrium shift to right/left - Conc will be Increased Fe3+ + SCN- Fe(SCN)+2(yellow)(red Blood)Click to view videoIncrease SCN- or Fe3+ Conc Decrease Fe3+ ConcEquilibrium shift to right By adding OH- will shift equilibrium to left Formation of complex ion Fe(SCN)2+ (red blood)Fe(SCN)2+ breakdown to form more Fe3+ (yellow) Decrease SCN- Conc By adding Ag+ will shift equilibrium to left Fe(SCN)2+ breakdown to form more SCN- (yellow) Increase Concentration Rate of reaction increase Rate constant - no change Kc, equilibrium constant - no changes Position of equilibrium shifted to a side to decrease concentration again 4. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established again Effect of Concentration on the position of equilibrium Increase in Conc - position of equilibrium shift to right/left - Conc will be Reduced Decrease in Conc position of equilibrium shift to right/left - Conc will be Increased 2CrO42- + 2H+ Cr2O72- + H2O(yellow)(orange)Click to view videoDecrease H+ Conc Increase H+ Conc 5. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established againEffect of Concentration on the position of equilibrium Increase in Conc - position of equilibrium shift to right/left - Conc will be Reduced Decrease in Conc position of equilibrium shift to right/left - Conc will be Increased 2CrO42- + 2H+ Cr2O72- + H2O (yellow)(orange) Click to view videoDecrease H+ ConcIncrease H+ Conc By adding OH- By adding H+Equilibrium shift to left Shift equilibrium to right Formation of CrO42- (yellow) Formation of Cr2O72- (orange) Increase Concentration Rate of reaction increase Rate constant - no change Kc, equilibrium constant - no changes Position of equilibrium shifted to a side to decrease concentration again 6. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established again Effect of Concentration on the position of equilibrium Increase in Conc - position of equilibrium shift to right/left - Conc will be Reduced Decrease in Conc position of equilibrium shift to right/left - Conc will be Increased CoCl42- + 6H2O Co(H2O)62+ + 4CI (blue)(pink) Click to view videoDecrease CI- Conc Increase H2O ConcIncrease CI- Conc 7. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established again Effect of Concentration on the position of equilibrium Increase in Conc - position of equilibrium shift to right/left - Conc will be Reduced Decrease in Conc position of equilibrium shift to right/left - Conc will be Increased CoCl42- + 6H2O Co(H2O)62+ + 4CI (blue)(pink)Click to view videoDecrease CI- Conc Increase H2O Conc Increase CI- ConcBy adding Ag+ to form AgCI By adding H2O By adding HCIEquilibrium shift to right Shift equilibrium to right Shift equilibrium to left Formation of Co(H2O)62+ (pink) Formation of Co(H2O)62+ (pink) Formation of CoCl42- (blue) Increase Concentration Rate of reaction increase Rate constant - no change Kc, equilibrium constant - no changes Position of equilibrium shifted to a side to decrease concentration again 8. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established againEffect of Pressure on the position of equilibriumIncrease in pressure - favour reaction with a decrease in pressure Decrease in pressure - favour reaction with an increase in pressure N2O4 (g) 2NO2(g) (colourless) (brown)Click to view videoIncreasing Pressure Decreasing Pressure 9. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancelout the effect of change and a new equilibrium can be established againEffect of Pressure on the position of equilibrium Increase in pressure - favour reaction with a decrease in pressure Decrease in pressure - favour reaction with an increase in pressure N2O4 (g) 2NO2(g)(colourless)(brown)Click to view videoIncreasing Pressure Decreasing Pressure By reducing Volume By Increasing Volume Equilibrium shift to left Equilibrium shift to right Less molecules on left side More molecules on right sidePressure drops Pressure increase Formation of N2O4 (colourless) Formation of NO2 (brown) Increase Pressure Rate of reaction increases Rate constant unchanged Position of equilibrium shift to reduce pressure Kc, equilibrium constant unchangedIncrease pressure collision more frequent - shift equilibrium to left - to reduce number of molecules - pressure decrease again Decrease pressure collision less frequent shift equilibrium to right to increase number of molecules pressure increase again 10. Factors affecting the position of Equilibrium Effect of Pressure on the position of equilibriumIncrease in pressure - favour reaction with a decrease in pressure Decrease in pressure - favour reaction with an increase in pressure N2O4 (g)2NO2(g) (colourless)(brown)Click to view videoIncreasing Pressure Decreasing Pressure N2(g) + 3H2(g) 2NH3(g)( 4 vol/moles ) (2 vol/moles)Increasing Pressure Decreasing Pressure 11. Factors affecting the position of EquilibriumEffect of Pressure on the position of equilibriumIncrease in pressure - favour reaction with a decrease in pressure Decrease in pressure - favour reaction with an increase in pressure N2O4 (g)2NO2(g) (colourless) (brown) Click to view videoIncreasing Pressure Decreasing Pressure By reducing Volume By Increasing Volume Equilibrium shift to left Equilibrium shift to right Less molecules on left side More molecules on right sidePressure drops Pressure increase Formation of N2O4 (colourless) Formation of NO2 (brown)N2(g) + 3H2(g) 2NH3(g)( 4 vol/moles )(2 vol/moles)Increasing Pressure Decreasing Pressure Equilibrium shift to right Equilibrium shift to left Less molecules on left side More molecules on right sidePressure drops Pressure increase Formation of NH3 (product) Formation of H2 and N2 (reactants) 12. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established again Effect of Temperature on the position of equilibrium Increase in Temp Favours endothermic reaction Absorb heat to reduce Temp again Decrease in Temp Favours exothermic reaction Release heat to increase Temp again CoCl42- + 6H2O Co(H2O)62+ + 4CI H = -ve (exothermic)(blue) (pink)Click to view video Increase Temp Decrease Temp 13. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established again Effect of Temperature on the position of equilibrium Increase in Temp Favours endothermic reaction Absorb heat to reduce Temp again Decrease in Temp Favours exothermic reaction Release heat to increase Temp again CoCl42- + 6H2O Co(H2O)62+ + 4CI H = -ve (exothermic)(blue)(pink)Click to view video Increase Temp Decrease Temp By Heating it up By Cooling it down Favours endothermic reaction Favours exothermic reaction Equilibrium shift to left Equilibrium shift to right To reduce Temp To increase Temp Formation of CoCl42- (blue) Formation of Co(H2O)62+ (pink) Increase Temperature Rate of reaction increases Rate constant also changes Rate of forward and Rate of reverse increases but to different extend Position of equilibrium shift to endothermic to decrease Temp Kc, equilibrium constant change 14. Factors affecting the position of EquilibriumLe Chateliers Principle A system in dynamic equilibrium is disturbed, the position of equilibrium will shift so as to cancel out the effect of change and a new equilibrium can be established again Effect of Temperature on the position of equilibrium Increase in Temp Favours endothermic reaction to absorb heat to reduc