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Template byBill Arcuri, WCSD

Click Once to BeginJEOPARDY!Chemistry Final Review

Chapter 8: Equilibrium


JEOPARDY!

100 100 100 100 100 100

200 200 200 200 200 200

300 300 300 300 300 300

400 400 400 400 400 400

500 500 500 500 500 500

EquilibriumEquilibrium Constants

LeChatelier’s Principle and

Reaction Quotients

LeChatelier’s Principle and

Reaction Quotients,

Part II

Calculations with Q and

KMisc.


Equilibrium - 100

What type of reaction occurs when reactants can form products and

products can form reactants?


Equilibrium - 100

Reversible Reactions


Equilibrium - 200

When is chemical equilibrium achieved?


Equilibrium - 200

When the rate of forward reaction equals

the rate of reverse reaction.


Equilibrium - 300

At which point is

equilibrium achieved?


Equilibrium - 300

B!!


Equilibrium - 400

Has a system at equilibrium stopped reacting? Why or

why not?


Equilibrium - 400

No. The system has reached dynamic equilibrium. The reaction keeps occurring,

but the rates of forward and reverse reaction are equal.


Equilibrium - 500

Does a Keq of 1 mean the reactant concentration

equals the product concentration?


Equilibrium - 500

No, not necessarily. The powers to which concentrations are raised

have a large effect on the value of Keq.

Ex. 2 A B; 2 M=[A], 4 M = [B]

Keq = 4/(2)2 = 4/4 = 1


Equilibrium Constants - 100

What is the general form of an equilibrium constant given:a A + b B c C + d D?



Keq = [C]cD]d

[A]a[B]b



Which of the following can be included in an equilibrium

expression:Solid

LiquidGas

Aqueous solution



Gas andAqueous solution



True or false: Equilibrium constants do NOT depend on temperature.



False. All equilibrium constants are dependent on temperature



An equilibrium constant much greater than 1 is a _____ favored

reaction. Conversely, an equilibrium constant that is much smaller than 1 is _____ favored.



1st blank: Product 2nd blank: Reactant



What are the units of an equilibrium constant?



There are none!!


LeChatelier’s Principle & Reaction Quotients - 100

Define LeChatelier’s Principle.



When a system at equilibrium is disturbed, the reaction will

counteract that shift in order to re-establish equilibrium.



Which side of the reaction will a system shift towards when reactants are added or products are removed?



To the right. (The products)



What is the difference between the reaction quotient (Q) and equilibrium constant (K)?



Reaction quotients are used at any concentrations while equilibrium

constants are only used for equilibrium concentrations.



N2 (g) + 3 H2 (g) 2 NH3 (g)

A system of the above reaction is at equilibrium. Which way will the

reaction shift if the volume decreases?



To the right. (The products side)


LeChatelier’s Principle & Reaction Quotients - 5002 SO2 (g) + O2 (g) 2 SO3 (g)

H = -197.8 kJ/mol

If heat is added to a system with the above reaction at equilibrium,

which direction will the reaction proceed?



To the left. (The reactants side)


LeChatelier’s Principle & Reaction Quotients II - 100

Q = KThe system is at ________.



Equilibrium!!



Q < KWhich direction will the system

shift?



To the right. (The prodcuts side)



The addition of an inert gas or pure solids to a system at equilibrium

results in a shift in which direction?



No change will occur since neither are included in the equilibrium

constant expression.



When Q > K, the reaction shifts left. Why?

Daily Double!!!



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 Keq



When will changing the volume of a gas container have no effect on

the system?



When equal number of moles of gas are on each side of the balanced

equation.


Calculations with Q and K- 100

Write the equilibrium expression for the given reaction:

2 NOCl (g) 2 NO (g) + Cl (g)



Keq = [NO]2[Cl] [NOCl]



Calculate Keq.N2 (g) + O2 (g) 2 NO (g)

When [N2] = .48 M; [O2] = .75 M and [NO] = .030 M



Keq = [NO]2

[N2] [O2]= (.030)2 / (.48) (.75)= .0025



Calculate Q and determine if the system is at equilibrium or not.

COCl2 CO (g) + Cl2 (g) & Keq = 170[CO]=[Cl2]=.15M and [COCl2] = .0011



Q = [CO][Cl2] [COCl2]

=(.15)(.15) / .0011= 20. The system is not at equilibrium



Calculate Q and determine which direction the system will shift.

H2 (g) + I2 (g) 2 HI (g)

[H2]= .150 M; [I2]= .175 M; and [HI]= .950 M

Keq = 50.5



Q = [HI]2

[H2][I2]= (.950)2 / (.175)(.150)= 34.4The system will shift right.



Find the equilibrium concentration of NO.

N2 (g) + O2 (g) 2 NO (g), Keq = .0025[N2]= .55 M; [O2] = .92 M



.0025 = [NO]2 / (.55)(.92)

.0025 = x2 / .506

.001265 = x2

.0356 M = x =[NO]


Misc. - 100

True or False: A combustion reaction can display an equilibrium.


Misc. - 100

False. The burning of something cannot be reversed.


Misc. - 200

A large Keq signals a product or reactant favored reaction?


Misc. - 200

Product favored.


Misc. - 300

Write the equilibrium expression.NaCl (s) + H2SO4 (l) HCl (g) + NaHSO4 (s)


Misc. - 300

Keq = [HCl]


Misc. - 400

H2 (g) + I2 (g) 2 HI (g)

Increasing the volume of a container with the above

equilibrium results in a shift in which direction?


Misc. - 400

No shift!! Equal number of moles of gas on each side of the equation.


Misc. - 500

N2 (g) + O2 (g) 2 NO (g), Keq = .0025[N2] = .81 M; [O2] = .75 M; and [NO] = .030 M

Find the value of Q and predict what direction the reaction will shift.


Misc. - 500

Q = [NO]2

[N2][O2]= (.030)2 / (.81)(.75)= .00148The reaction will shift right.


Final Jeopardy

What is the use of an equilibrium constant?


Click Once to Begin

An equilibrium constant is a mathematical representation of

the ratio of products to reactants in a system at

equilibrium.

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