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Chemical Equilibrium

Total questions: 20

Worksheet time: 19mins

Name
Class
Date
1.

This following is true about the graph of the concentration of reactant and products againts time except:

a)

[A] decrease

b)

The system is in the state of equilibrium

c)

[B] decrease with time

d)

After certain time, [A] and [B] remains unchanged, but the reaction did not stop

2.

At equilibrium, __________.

a)

all chemical reactions have ceased

b)

the rates of the forward and reverse reactions are equal

c)

the rate constants of the forward and reverse reactions are equal

d)

the value of the equilibrium constant is 1

e)

) the limiting reagent has been consumed

3.

2A + 3B <----> 2AB

The forward reaction forms the substance __________.

a)

A

b)

AB

c)

B

d)

A + B

4.

Define chemical equilibrium.

a)

A reaction is reversible.

b)

A state where the concentration of the reactants is equal to the concentration of the products.

c)

A state where the rate of a forward reaction is equal to the rate of the reverse reaction.

d)

A state where the reaction stops and no further change in concentration occurs.

5.
What is the Kc expression for this reaction?
   2 NO(g)  +  O2(g) ⇌  2 NO2(g)
a)
K= [NO2]2 / [NO][O2]
b)
K=  [NO][O2] / [NO2]2
c)
K= [NO][O2] [NO2]2
d)
K= [NO2]2 / [NO]2 +  [O2]
6.
What are [A] and [B]?
a)
concentration of reactants
b)
concentration of products
c)
energy of reactants
d)
energy of products
7.
What is the equilibrium expression for:
Fe3O4(s) + 4H2(g) <=> 3Fe(s) + 4H2O(g)
Kc =
a)
[Fe][H2O]4  / [Fe3O4] [H2]4
b)
[Fe3O4] [H2]/  [Fe][H2O]4
c)
[H2O]4 / [H2]4
d)
[Fe] [H2O] / [Fe3O4] [H2]
8.

The Kc expression for the reaction 2NH3 ⇌ N2 + 3H2

a)
b)
c)
d)
9.

If the reaction quotient Q has a smaller value than the related equilibrium constant, K, _________

a)

the reaction is at equilibrium

b)

the reaction is not at equilibrium, and will make more products at the expense of the reactants

c)

the reaction is not at equilibrium, and will make more reactants at the expense of the products

d)

the value of K will not increase until it is equal to Q

10.

At elevated temperatures ammonium carbonate, NH2COONH4, is in equilibrium with NH3 and CO2 according to the equation;

NH2COONH4(s) ↔ 2 NH3(g) + CO2(g)

What is the equilibrium expression for this reaction?

a)

K = 2 [NH3][CO2]

[NH2COONH4]

b)

K = [NH3]2[CO2]

[NH2COONH4]

c)

K = 2 [NH3][CO2]

d)

K = [NH3]2[CO2]

11.

2SO2(g)+O2(g) ⇌ 2SO3(g) + Heat


Adding SO2(g) will

a)

shift equilibrium right

b)

shift equilibrium left

c)

increase rate of reaction

d)

have no change

12.

2SO2(g)+O2(g) ⇌ 2SO3(g) + Heat


Increasing the temperature will...

a)

shift equilibrium right

b)

shift equilibrium left

c)

increase pressure

d)

have no change

13.

CoCI42- +6H2O →Co(H2O)62+ + 4CI-.


What would happen when H2O is added?

a)

Position of equilibrium will shift to left (and become more blue)

b)

Position of equilibrium will shift to right (and become more pink)

c)

Keq will increase as H2O is added

d)

Position of equilibrium will shift to left to reduce the added H2O

14.

1N2 + 3H2 →2NH3


When the pressure on the system is increased, the equilibrium position shifts to the right. Why?

a)

To increase the amount of products

b)

To reduce the pressure, as the right side has fewer molecules of gas

c)

Keq will increase when it is shifted to the right

d)

To increase the pressure, as the right side has more molecules of gas

15.

2CrO42- + 2H+ → Cr2O72- + H2O


What will happen when H+ ions are added to the system?

a)

Position of equilibrium will shift to left and become more yellow

b)

Color of system will turn all yellow

c)

Color of system will turn all orange

d)

Equilibrium will shift to right and become more orange

16.
The following statement is true for catalyst EXCEPT
a)
Increase the forward and reverse rate by the same extent
b)
Position of equilibrium will not change
c)
Kc remains the same.
d)
Position of equilibrium shift to right, more product formed.
17.
The following statement is true on the effect of increasing concentration EXCEPT
a)
Increase concentration increases the rate
b)
Increase concentration has no effect on rate constant
c)
Increase concentration increases Kc
d)
Increase concentration changes the equilibrium composition.
18.
Changes in pressure will only affect substances that are in the __________ state.
a)
gaseous
b)
liquid
c)
solid
d)
plasma
19.

In which of the following systems would the number of moles of the substances present at equilibrium NOT be shifted by a change in the volume of the system at constant temperature?

a)

CO(g) + NO(g) ↔ CO2(g) + ½N2(g)

b)

N2(g) + 3H2(g) ↔ 2NH3(g)

c)

N2(g) + 2O2(g) ↔ 2 NO2(g)

d)

NO(g) + O3(g) ↔ NO2(g) + O2(g)

20.

At what time (in seconds) is equilibrium established?

a)

0 seconds

b)

1 second

c)

5 seconds

d)

10 seconds