© University of South Carolina Board of Trustees K eq is Linked to a Chemical Equation multiplication 2 O 3(g)  3 O 2(g) O 3(g)  3 / 2 O 2(g) 1 / 2  { 2 O 3(g)  3 O 2(g) }

K eq is Linked to a Chemical Equation multiplication © University of South Carolina Board of Trustees 2 O 3(g)  3 O 2(g) O 3(g)  3 / 2 O 2(g) 1 / 2 1 / 2  { 2 O 3(g)  3 O 2(g) }

© University of South Carolina Board of Trustees 2 O 3(g)  3 O 2(g) O 3(g)  3 / 2 O 2(g) 1 / 2  { 2 O 3(g)  3 O 2(g) } K eq is Linked to a Chemical Equation multiplication

© University of South Carolina Board of Trustees K eq is Linked to a Chemical Equation inversion 2 O 3(g)  3 O 2(g) 3 O 2(g)  2 O 3(g) -1  { 2 O 3(g)  3 O 2(g) }

© University of South Carolina Board of Trustees K eq is Linked to a Chemical Equation inversion 2 O 3(g)  3 O 2(g) 3 O 2(g)  2 O 3(g) -1  { 2 O 3(g)  3 O 2(g) }

© University of South Carolina Board of Trustees K eq is Linked to a Chemical Equation inversion 2 O 3(g)  3 O 2(g) 3 O 2(g)  2 O 3(g) -1  { 2 O 3(g)  3 O 2(g) }

© University of South Carolina Board of Trustees Given:N 2 O 4(g)  2 NO 2(g) K eq = 4.63 x10 -3 (a) determine K′ eq for the reaction 2 NO 2(g)  N 2 O 4(g) (b) determine K″ eq for the reaction NO 2(g)  1 / 2 N 2 O 4(g) Student Example

© University of South Carolina Board of Trustees Standard Concentration Units Liquid[ A (l) ] Molarity mol/L Kc Kc Gas P A Partial Pressure atm or Torr [ A (g) ] Molarity mol/L KP KP

© University of South Carolina Board of Trustees K c vs K P N 2 O 4(g)  2 NO 2(g) MolarityPartial Pressure

© University of South Carolina Board of Trustees K c vs K P N 2 O 4(g)  2 NO 2(g) MolarityPartial Pressure Here:  n gas = n gas,final - n gas,initial = 2 -1 = +1 In General:

© University of South Carolina Board of Trustees K c vs K P N 2 O 4(g)  2 NO 2(g) MolarityPartial Pressure Here:  n gas = n gas,final - n gas,initial = 2 -1 = +1 In General:

© University of South Carolina Board of Trustees Chapt. 14 Chemical Equilibrium Q versus K eq Sec. 2 Which Direction Will a Reaction Go to Reach Equilibrium? Q versus K eq

© University of South Carolina Board of Trustees The Reaction Quotient 2NO 2  N 2 O 4 Q < K eq Q > K eq

© University of South Carolina Board of Trustees Example 2 NO 2(g)  N 2 O 4(g) K c = 135 ° C

© University of South Carolina Board of Trustees Student Example CH 4(g) + H 2 O (g)  CO (g) + 3 H 2(g) K c = 5.67 Determine the direction of reaction when the initial concentrations are: [CH 4 ] = M[H 2 O] = M [CO] = M[H 2 ] = M

© University of South Carolina Board of Trustees Which Direction Will a Reaction Go to Reach Equilibrium? Compare Q to K eqCompare Q to K eq OR Le Chatlier’s PrincipleLe Chatlier’s Principle

© University of South Carolina Board of Trustees Chapt. 14 Chemical Equilibrium Le Chatlier’s Principle Sec. 3 Which Direction Will a Reaction Go to Reach Equilibrium? Le Chatlier’s Principle

© University of South Carolina Board of Trustees Le Chatelier’s Principle An equilibrium shifts in response to an external change (“stress”) in the direction that reduces the “stress.”

© University of South Carolina Board of Trustees Le Chatelier’s Principle An equilibrium shifts in response to an external change (“stress”) in the direction that reduces the “stress.” Chemical “Stresses”: Adding/removing one substance Changing the volume Changing the temperature

© University of South Carolina Board of Trustees Le Chatelier’s Principle An equilibrium shifts in response to an external change (“stress”) in the direction that reduces the “stress.” Chemical “Stresses”:  Adding/removing one substance Changing the volume Changing the temperature

© University of South Carolina Board of Trustees Le Chatelier’s Principle An equilibrium shifts in response to an external change (“stress”) in the direction that reduces the “stress.” Chemical “Stresses”: Adding/removing one substance  Changing the volume Changing the temperature

© University of South Carolina Board of Trustees Le Chatelier’s Principle An equilibrium shifts in response to an external change (“stress”) in the direction that reduces the “stress.” Chemical “Stresses”: Adding/removing one substance Changing the volume  Changing the temperature

© University of South Carolina Board of Trustees Le Chatelier’s Principle An equilibrium shifts in response to an external change (“stress”) in the direction that reduces the “stress.” Chemical “Stresses”: Adding/removing one substance Changing the volume  Changing the temperature (see p. 482)