By : Sarah Dippelhofer

Basic Concep t of Equili brium Equili brium Consta nts Reacti on Quotie nts LeChat elier ’ s Princi ple Miscel laneou s

Basic Concept of Equilibrium -100 What is the definiti on of Equilibr ium?

Click here to return to game Equilibrium - When the rate of the forward reaction equals the rate of the reverse reaction in a chemical reaction.

Basic Concept of Equilibrium -200 In order for a reaction to occur, what must happen according to the collision theory?

Click here to return to game According to the collision theory, molecules must collide at the correct orientation and with the minimum amount of energy to begin the reaction in order for the reaction to occur.

Basic Concept of Equilibrium -300  In the following diagram, what do A, B, and C represent? A B C

Click here to return to game A: Forward Reaction B: Point at which Equilibrium is reached C: Reverse Reaction

Basic Concept of Equilibrium -400 Explain the term Dynamic Equilibriu m

Click here to return to game  Dynamic Equilibrium - when the reaction proceeds in both the forward and reverse directions at the same rate. At this state the products and reactants no longer change. This makes it seem as though the reaction has stopped.

Basic Concept of Equilibrium -500 Which of the following glasses contains substances involved in a reaction that can achieve equilibrium? How can you tell? Once at equilibrium, do the amount of products and reactants change? ABC

Click here to return to game  Glass C contains substances that can react and reach equilibrium. It is easy to identify that the reaction in glass C can reach equilibrium because it is the only reaction with a double arrow ( an arrow facing toward and an arrow facing away from the reactants ). This indicates that the reaction occurs in the forward and reverse directions, which is necessary for a reaction to reach equilibrium. At equilibrium, amount of products and reactants remains constant.

Equilibrium Constants Define the Equilibriu m Constant Expression

Click here to return to game Equilibrium Constant Expression - an equation showing the ratio of the concentrations of products to reactants at equilibrium

Equilibrium Constants -200

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Equilibrium Constants -300

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Equilibrium Constants -400

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Equilibrium Constants -500

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Reaction Quotients -100  What is the difference between the equilibrium constant and the reaction quotient?

Click here to return to game  The equilibrium constant is at equilibrium and the reaction quotient is at any point in the reaction.

Reaction Quotients -200  In the following siduations, where does the reaction lie ( which reaction has the fastest rate ) ? Q = K Q > K Q < K

Click here to return to game  Q = K - System is at equilibrium  Q > K - System will make more reactants to reach equilibrium ( lies to the left to make more reactants, so reverse reaction rate is faster )  Q < K - System will make more products to reach equilibrium ( lies to the right to make more products, so forward reaction rate is faster )

Reac tion Quotients -300

Click here to return to game  The reaction DOES NOT LIE IN ANY DIRECTION, because it is at equilibrium  If K = Q ( which in this case it does ), than the system is at equilibrium and both reactions are occurring at the same rate

Reaction Quotients -400 For N 2 ( g ) + O 2 ( g )  2 NO ( g ) If [ N 2 ] = 0.71 M, [ O 2 ] = 0.78 M and [ NO ] = M, is the reaction at equilibrium if K = ? If not, which direction will lie to reach equilibrium?

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Reaction Quotients Write the reaction quotient expression for the reaction 2. If the concentration of acetate is.34 M, the concentration of hydronium is.65 M, and the concentration of acetic acid is.97 M, what is the reaction quotient? 3. If the equilibrium constant is.3467, where does the system lie? Explain your reasoning.

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LeChatelier ’ s Principle -100 Define LeChatelier ’ s Principle

Click here to return to game  Le Chatelier ’ s Principle – If a system at equilibrium is disturbed, it will shift to re - establish equilibrium  In other words, a system will do what ever it takes to adjust the system so that it establishes equilibrium

LeChatelier ’ s Principle -200 Explain how adding concentrations and decreasing concentrations in a system can establish equilibrium.

Click here to return to game  Adding more products if a reaction lies to the left ( Q < K ) will help the system establish equilibrium because more products would shift the system further to the left, increasing the reverse reaction rate, which leads to establishing equilibrium. Decreasing the concentration of reactants will have the same effect.  Adding more reactant if a reaction lies to the right ( Q < K ) will help the system establish equilibrium because it shifts the reaction lies to increase the rate of the forward reaction. Decreasing the concentration of products will have the same effect.

LeChatelier ’ s Principle -300  Complete the chart about changes in pressure affecting equilibrium :

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LeChatelier ’ s Principle -400 Complete the missing spaces in the chart:

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LeChatelier ’ s Principle -500  Which way would the following changes cause the system to shift given the reaction : NH 4 Cl ( s )  NH 3 ( g ) + HCl ( g ) 1. Add NH 3 2. Decrease HCl 3. Increase Pressure 4. Decrease Volume

Click here to return to game  1. shift to left because more product was added  2. Shift to the right because product was less concentrated compared to reactants  Shift left because there are less moles on the reactants side ( ratio of reactants moles to product moles is 1:2)  Shift right because increased volume means pressure decreased and a decrease and pressure shifts to what side has the least moles. In this reaction, the reactants have less moles.

Miscellaneou s -100 What is the difference between Homogeneous Equilibrium and Heterogeneou s Equilibrium?

Click here to return to game  Heterogeneous Equilibrium – There are at least 2 states of matter Ex :  Homogeneous Equilibrium – All of the species are the same state of matter Ex : 2 H 2 (g) + O 2 (g)  2 H 2 O (g) 2 H 2 (g) + O 2 (g)  2 H 2 O (l)

Miscellaneou s -200  What are the two states of matter that are not included in an equilibrium constant expression or reaction quotient expression?

Click here to return to game  Solids and Liquids are not included in wither expression  Only Gases and aqueous solutions are included in the expressions

Miscellaneou s What is the equilibrium constant expression for this reaction? 2. If the equilibrium constant is 1.33, what is the concentration of CO 2 at equilibrium if the concentration of NaOH is.230 M and the concentration of NaHCO 3 is.743 M?

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Miscellaneou s -400  What are the changes that have no affect in the rates of equations in a system shifting? ( Explain at least 3 of the 4)

Click here to return to game 1. Adding a pure solid or liquid will not make a difference because they are not included in equilibrium expressions. 2. Increasing pressure by adding an inert gas will not make a difference because they are also not in the equilibrium constant expression. 3. Changing the volume when there are an even number of moles on each side won ’ t change anything because equal moles means the pressures can not be changed. 4. Adding a catalyst will not make a difference because it ’ s not included in the reaction ; it only speeds up the reaction.

Miscellaneou s -500  2 SO 2 (g) + O 2 (g)  2 SO 3 (g) an exothermic reaction  How will the following affect the system : 1. Decreasing the heat 2. Increasing the heat 3. Increasing the volume 4. Removing the O 2

Click here to return to game 1. Shift to the right because the heat in an exothermic reaction is a product, when product is decreased, more must form to it shifts to the right 2. Shift to the left because more product ( the heat ) was added, more reactants must be made to level out the reaction rates to equilibrium 3. Increasing the volume increases the pressure, the reaction thus shifts to the right because there are less mole of product than reactant 4. Removing O 2 ( a reactant ) causes the reaction to shift left to form more reactants to replace the O 2 lost