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Le Chateleir

Total questions: 25

Worksheet time: 17mins

Name
Class
Date
1.
An equilibrium constant with a large magnitude indicates…
a)
A very fast reaction
b)
More products at equilibrium
c)
More reactants at equilibrium
d)
nothing, without considering the stoichiometry of the reaction
2.
Why is equilibrium called a dynamic state?
a)
Chemists try to convert as much reactants as possible into products.
b)
The reactions at equilibrium continue to take place once equilibrium is established.
c)
The products of a forward reaction are favored, so equilibrium lies to the right.
d)
All chemical reactions are considered to be reversible under suitable conditions.
3.
At what time (in seconds) is equilibrium established?
a)
0 seconds
b)
1 second
c)
5 seconds
d)
10 seconds
4.
Le Chaltelier's Principle states that if a chemical system at equilibrium is stressed,
a)
the system will adjust to increase the stress
b)
the system will adjust to reduce the stress
c)
the system will not adjust
5.
When writing an endothermic reaction, heat energy is stated as
a)
product
b)
catalyst
c)
reactant
6.
An exothermic reaction is allowed to reach equilibrium. If heat energy is then removed, the equilibrium will shift
a)
toward the middle
b)
toward the reactant side
c)
toward the product side
7.
Which of the following is NOT true at equilibrium?
a)
The forward and reverse reactions proceed at the same rate.
b)
The concentrations of reactants and products do not change.
c)
The concentration of the reactants is equal to the concentration of the products.
d)
The forward and reverse reactions continue to occur.
8.
For the reaction...
SO2(g) + O2(g) <−>  SO3(g)
If the concentration of 
SO2(g)  is increased, the equilibrium of the reaction will ___________.
a)
shift to the left
b)
shift to the right
c)
not shift
9.
For the reaction...
SO2(g) + O2(g) <−>  SO3(g)

If the equilibrium shifts to the right, the concentration of O2(g) will ___________.
a)
increase
b)
decrease
c)
remain the same
10.
For the reaction...
energy +  N2(g)  +  O2(g)  <−>  2NO(g)
If  O2(g) is removed, the  concentration of N2 will _______.
a)
increase
b)
decrease
c)
remain the same
d)
double
11.
A +  B <--> C + D   ΔH= 151kJ
Rewrite the above equation with energy as a reactant or product:
a)
A +  B <--> C + D + energy
b)
A +  B + energy <--> C + D 
12.
For the reaction...
heat  +  N2(g)  +  O2(g)  <−>  2NO(g)
If the heat is removed to the chemical system, the equilibrium will _______.
a)
shift to the left
b)
shift to the right
c)
not shift
13.
For the reaction...
N2 (g) +  3 H2 (g) <−> 2 NH3 (g)

If the pressure in the system is increased, the reaction will __________________.
a)
 shift to the left
b)
shift to the right
c)
not shift
14.
When  ΔH  is negative it represents a(n)
a)
exothermic reaction 
b)
endothermic reaction 
15.
The three factors that affect the equilibrium of a reaction are temperature, pressure and __________. 
a)
energy
b)
concentration 
c)
enthalpy 
d)
ice 
16.
  A(g) + B(aq) <> C(s) 
 ΔHrxn= -453 kJ/mol
If the [B] is decreased then the reaction is will shift to the _______. 
a)
Left
b)
Right
c)
Stays the same 
d)
Up
17.
 A(g) + B(aq) <> C(s)  + D(s) 
ΔHrxn= 240 kJ/mol
If the pressure decreases then the reaction will shift to the _____. 
a)
left
b)
right
c)
stays the same 
d)
Up
18.
What is the proper Keq for the following reaction? 
   2 NO(g)  +  O2(g) ⇌ 2 NO2(g)
a)
Keq = [NO2]2 / [NO]2[O2]
b)
Keq =  [NO]2[O2] / [NO2]2
c)
Keq = [NO]2[O2][NO2]2
d)
Keq = 2[NO][O2] / 2[NO2]
19.
What is [A] and [B]?
a)
Concentration of Reactants
b)
Concentration of Products
c)
Energy of Reactants
d)
Energy of Products
20.
When Keq > 1, 
a)
There are more products than reactants when the reaction reached equilibrium.
b)
There are more reactant than products when the reaction reached equilibrium.
c)
The amount of reactants is equal to the amount of products.
21.
Given: 2A(g) <-> 2B(g) + C(g). At a particular temperature, K = 1.6x104.
Raising the pressure by lowering the volume of the container will...
a)
cause [A] to increase
b)
cause [B] to increase
c)
have no effect
d)
cannot be determined
22.
Given: 2A(g) <-> 2B(g) + C(g). At a particular temperature, K = 1.6x104.
At a higher temperature, K = 1.8x10-5. Placing the equilibrium mixture in an ice bath (thus lowering the temperature) will...
a)
cause [A] to increase
b)
cause [B] to increase
c)
gave no effect
d)
cannot be determined
23.
At what time does the reaction reach equilibrium?
a)
t1
b)
t2
c)
t3
d)
t4
24.
2SO2(g)+O2(g)⇌2SO3(g)
Removing O2(g) will
a)
shift equilibrium right
b)
shift equilibrium left
c)
decrease temperature
d)
have no change
25.
2SO2(g)+O2(g)⇌2SO3(g) is an exothermic reaction.
an in Increase temperature will...
a)
shift equilibrium toward the right
b)
shift equilibrium toward the left
c)
increase pressure
d)
have no change