Template by Bill Arcuri, WCSD Click Once to Begin JEOPARDY! Chemistry Final Review Chapter 8: Equilibrium

Template by Bill Arcuri, WCSD JEOPARDY! Equilibrium Equilibrium Constants LeChatelier’s Principle and Reaction Quotients LeChatelier’s Principle and Reaction Quotients, Part II Calculations with Q and K Misc.

Template by Bill Arcuri, WCSD Daily Double Graphic and Sound Effect! DO NOT DELETE THIS SLIDE! Deleting it may cause the game links to work improperly. This slide is hidden during the game, and WILL not appear. In slide view mode, copy the above (red) graphic (click once to select; right click the border and choose “copy”). Locate the answer slide which you want to be the daily double Right-click and choose “paste”. If necessary, reposition the graphic so that it does not cover the answer text. Daily Double!!!

Template by Bill Arcuri, WCSD Equilibrium What type of reaction occurs when reactants can form products and products can form reactants?

Template by Bill Arcuri, WCSD Equilibrium Reversible Reactions

Template by Bill Arcuri, WCSD Equilibrium When is chemical equilibrium achieved?

Template by Bill Arcuri, WCSD Equilibrium When the rate of forward reaction equals the rate of reverse reaction.

Template by Bill Arcuri, WCSD Equilibrium At which point is equilibrium achieved?

Template by Bill Arcuri, WCSD Equilibrium B!!

Template by Bill Arcuri, WCSD Equilibrium Has a system at equilibrium stopped reacting? Why or why not?

Template by Bill Arcuri, WCSD Equilibrium No. The system has reached dynamic equilibrium. The reaction keeps occurring, but the rates of forward and reverse reaction are equal.

Template by Bill Arcuri, WCSD Equilibrium Does a K eq of 1 mean the reactant concentration equals the product concentration?

Template by Bill Arcuri, WCSD Equilibrium No, not necessarily. The powers to which concentrations are raised have a large effect on the value of K eq. Ex. 2 A  B; 2 M=[A], 4 M = [B] K eq = 4/(2) 2 = 4/4 = 1

Template by Bill Arcuri, WCSD Equilibrium Constants What is the general form of an equilibrium constant given: a A + b B  c C + d D?

Template by Bill Arcuri, WCSD Equilibrium Constants K eq = [C] c D] d [A] a [B] b

Template by Bill Arcuri, WCSD Equilibrium Constants Which of the following can be included in an equilibrium expression: Solid Liquid Gas Aqueous solution

Template by Bill Arcuri, WCSD Equilibrium Constants Gas and Aqueous solution

Template by Bill Arcuri, WCSD Equilibrium Constants True or false: Equilibrium constants do NOT depend on temperature.

Template by Bill Arcuri, WCSD Equilibrium Constants False. All equilibrium constants are dependent on temperature

Template by Bill Arcuri, WCSD Equilibrium Constants An equilibrium constant much greater than 1 is a _____ favored reaction. Conversely, an equilibrium constant that is much smaller than 1 is _____ favored.

Template by Bill Arcuri, WCSD Equilibrium Constants st blank: Product 2 nd blank: Reactant

Template by Bill Arcuri, WCSD Equilibrium Constants What are the units of an equilibrium constant?

Template by Bill Arcuri, WCSD Equilibrium Constants There are none!!

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients Define LeChatelier’s Principle.

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients When a system at equilibrium is disturbed, the reaction will counteract that shift in order to re- establish equilibrium.

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients Which side of the reaction will a system shift towards when reactants are added or products are removed?

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients To the right. (The products)

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients What is the difference between the reaction quotient (Q) and equilibrium constant (K)?

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients Reaction quotients are used at any concentrations while equilibrium constants are only used for equilibrium concentrations.

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients N 2 (g) + 3 H 2 (g)  2 NH 3 (g) A system of the above reaction is at equilibrium. Which way will the reaction shift if the volume decreases?

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients To the right. (The products side)

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients SO 2 (g) + O 2 (g)  2 SO 3 (g) H = kJ/mol If heat is added to a system with the above reaction at equilibrium, which direction will the reaction proceed?

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients To the left. (The reactants side)

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II Q = K The system is at ________.

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II Equilibrium!!

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II Q < K Which direction will the system shift?

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II To the right. (The prodcuts side)

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II The addition of an inert gas or pure solids to a system at equilibrium results in a shift in which direction?

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II No change will occur since neither are included in the equilibrium constant expression.

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II When Q > K, the reaction shifts left. Why? Daily Double!!!

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II The ratio of products to reactants is too high. Shifting left makes more reactants and increases the value of the denominator in the equilibrium expression, thus lowering the value of K eq

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II When will changing the volume of a gas container have no effect on the system?

Template by Bill Arcuri, WCSD LeChatelier’s Principle & Reaction Quotients II When equal number of moles of gas are on each side of the balanced equation.

Template by Bill Arcuri, WCSD Calculations with Q and K- 100 Write the equilibrium expression for the given reaction: 2 NOCl (g)  2 NO (g) + Cl (g)

Template by Bill Arcuri, WCSD Calculations with Q and K- 100 K eq = [NO] 2 [Cl] [NOCl]

Template by Bill Arcuri, WCSD Calculations with Q and K- 200 Calculate K eq. N 2 (g) + O 2 (g)  2 NO (g) When [N 2 ] =.48 M; [O 2 ] =.75 M and [NO] =.030 M

Template by Bill Arcuri, WCSD Calculations with Q and K- 200 K eq = [NO] 2 [N 2 ] [O 2 ] = (.030) 2 / (.48) (.75) =.0025

Template by Bill Arcuri, WCSD Calculations with Q and K- 300 Calculate Q and determine if the system is at equilibrium or not. COCl 2  CO (g) + Cl 2 (g) & K eq = 170 [CO]=[Cl 2 ]=.15M and [COCl 2 ] =.0011

Template by Bill Arcuri, WCSD Calculations with Q and K- 300 Q = [CO][Cl 2 ] [COCl 2 ] =(.15)(.15) /.0011 = 20. The system is not at equilibrium

Template by Bill Arcuri, WCSD Calculations with Q and K- 400 Calculate Q and determine which direction the system will shift. H 2 (g) + I 2 (g)  2 HI (g) [H 2 ]=.150 M; [I 2 ]=.175 M; and [HI]=.950 M K eq = 50.5

Template by Bill Arcuri, WCSD Calculations with Q and K- 400 Q = [HI] 2 [H 2 ][I 2 ] = (.950) 2 / (.175)(.150) = 34.4 The system will shift right.

Template by Bill Arcuri, WCSD Calculations with Q and K- 500 Find the equilibrium concentration of NO. N 2 (g) + O 2 (g)  2 NO (g), K eq =.0025 [N 2 ]=.55 M; [O 2 ] =.92 M

Template by Bill Arcuri, WCSD Calculations with Q and K = [NO] 2 / (.55)(.92).0025 = x 2 / = x M = x =[NO]

Template by Bill Arcuri, WCSD Misc True or False: A combustion reaction can display an equilibrium.

Template by Bill Arcuri, WCSD Misc False. The burning of something cannot be reversed.

Template by Bill Arcuri, WCSD Misc A large K eq signals a product or reactant favored reaction?

Template by Bill Arcuri, WCSD Misc Product favored.

Template by Bill Arcuri, WCSD Misc Write the equilibrium expression. NaCl (s) + H 2 SO 4 (l)  HCl (g) + NaHSO 4 (s)

Template by Bill Arcuri, WCSD Misc K eq = [HCl]

Template by Bill Arcuri, WCSD Misc H 2 (g) + I 2 (g)  2 HI (g) Increasing the volume of a container with the above equilibrium results in a shift in which direction?

Template by Bill Arcuri, WCSD Misc No shift!! Equal number of moles of gas on each side of the equation.

Template by Bill Arcuri, WCSD Misc N 2 (g) + O 2 (g)  2 NO (g), K eq =.0025 [N 2 ] =.81 M; [O 2 ] =.75 M; and [NO] =.030 M Find the value of Q and predict what direction the reaction will shift.

Template by Bill Arcuri, WCSD Misc Q = [NO] 2 [N 2 ][O 2 ] = (.030) 2 / (.81)(.75) = The reaction will shift right.

Template by Bill Arcuri, WCSD Final Jeopardy What is the use of an equilibrium constant?

Template by Bill Arcuri, WCSD Click Once to Begin An equilibrium constant is a mathematical representation of the ratio of products to reactants in a system at equilibrium.