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Worksheets

Equilibrium

Total questions: 25

Worksheet time: 23mins

Name
Class
Date
1.

For the reaction 2H2S(g)<---> 2H2(g) + S2(g), kp= 2.4 x10-4 at 1073 K. A reaction mixture contains 0.112 atm H2, 0.055 atm of S2 and 0.445 atm of H2S. Is the reaction at equilibrium? if not, which way will it proceed

a)

Yes it is at equilibrium

b)

No, to the right

c)

No, to the left.

2.
What are the two factors to look for when determining if the reaction is at equilibrium?
a)
Forward reaction rate is faster than the reverse and concentrations are equal
b)
Forward and reverse reaction rates are equal and concentration is conctant
c)
Forward and revers reaction rates are equal and concentration is equal
d)
Forward reaction rate is faster than the reverse and concentration is equal
3.
At what time the reaction reached equilibrium?
a)
t1
b)
t2
c)
t3
d)
t4
4.
For the reaction...
SO2 + O2  <=>  SO3
If the concentration of SOis increased, the equilibrium position of the reaction will shift ___________.
a)
to the left
b)
to the right
c)
to the left and right 
d)
neither left nor right
5.
For the reaction...
SO2 + O2 <=>  SO3
If the equilibrium position shifts to the right, the concentration of O2 will ___________.
a)
increase
b)
decrease
c)
remain the same
d)
double
6.
For the reaction...
N2  +  O2  <=>  2NO
If  O2 is removed, the  concentration of N2 will _______.
a)
increase
b)
decrease
c)
remain the same
d)
double
7.
For the reaction...
N2 (g) +  3 H2 (g) <=> 2 NH3 (g)

If the pressure in the system is increased,  which substance(s) will increase in concentration?
a)
N (as 2 mol gas  → 4 mol gas)
b)
H2 (as 2 mol gas  → 4 mol gas)
c)
N2 and H(as 2 mol gas  → 4 mol gas)
d)
NH3 (as 4 mol gas  → 2 mol gas)
8.
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]
9.
Consider the following reaction:
2SO2(g) + O2(g) <=> 2SO3(g) 
ΔΗ = - 197 kJ mol -1
Which of the following will NOT shift the equilibrium position to the right?
a)
Adding more O2
b)
Adding a catalyst
c)
increasing the pressure
d)
Lowering the temperature
10.
An equilibrium constant with a large value, e.g. Kc = 1000, indicates…
a)
A very fast reaction
b)
Mostly products at equilibrium
c)
Mostly reactants at equilibrium
d)
Nothing useful at all
11.
Le Chatelier's Principle states that.... 
If a (dynamic) equilibrium is disturbed by changing the conditions, the position of equilibrium................
a)
moves to increase the change
b)
moves to counteract the change
c)
does not change
12.

Hydrogen can be produced by this reaction.


CO(g) + H2O(g) ⇌ CO2(g) + H2(g)


In an experiment 4.20 mol of carbon monoxide were mixed with 2.00 mol of steam. When the reaction reached equilibrium, 1.60 mol of hydrogen had been formed.


What is the value of the equilibrium constant, Kc, for this reaction?

a)

0.30

b)

0.41

c)

1.54

d)

2.46

13.

When one mole of ammonia is heated to a given temperature, 50% of the compound dissociates and the following equilibrium is established.


NH3(g) ⇌ 0.5N2(g) + 1.5H2(g)


What is the total number of moles of gas present in this equilibrium mixture?

a)

1.5

b)

2.0

c)

2.5

d)

3.0

14.

A and B react together in this reversible reaction.


A + 3BC + 2D


A mixture of 10 mol of A and 10 mol of B were left to reach equilibrium. The equilibrium mixture contained 4 mol of B.


What is the total amount, in moles, of substances in the equilibrium mixture?

a)

14

b)

16

c)

18

d)

20

15.

Hydrogen is produced by the reaction of methane with steam. The reaction mixture reaches a state of dynamic equilibrium.


CH4(g) + H2O(g) ⇌ CO(g) + 3H2(g) ∆H = +206 kJ mol−1


Which of the following shows how the equilibrium yield of hydrogen and the value of the equilibrium constant are affected by the changes shown?

a)

Change: Increase pressure

Effect on equilibrium yield of H2(g): decrease

Effect on value of Kc: decrease

b)

Change: Add a catalyst

Effect on equilibrium yield of H2(g): increase

Effect on value of Kc: no effect

c)

Change: Increase temperature

Effect on equilibrium yield of H2(g): increase

Effect on value of Kc: increase

d)

Change: Remove CO(g) as formed

Effect on equilibrium yield of H2(g): increase

Effect on value of Kc: increase

16.

Methanol is synthesised from carbon monoxide and hydrogen according to the equation below.


CO(g) + 2H2(g)⇌ CH3OH(g) ∆H = −91 kJ mol−1


Which one of the following changes would not affect the value of the equilibrium constant and would not increase the yield of methanol?

a)

increase in temperature

b)

decrease in temperature

c)

increase in pressure

d)

decrease in pressure

17.

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]

18.
Changes in pressure will only affect substances that are in the __________ state.
a)
gaseous
b)
liquid
c)
solid
d)
plasma
19.
What is the equilibrium-constant expression for 
CO2(g) + H2(g) ↔ CO(g) + H2O(l)
a)
Kc= [CO][H2O] / [CO2][H2]  
b)
Kc= [CO2][H2] / [CO]
c)
Kc= [CO2][H2] / [CO][H2O]
d)
Kc= [CO] / [CO2][H2]  
20.
For the reaction...
heat  +  N2  +  O2  ↔  2NO
If the heat is added to the chemical system, the equilibrium will shift _______.
a)
left
b)
right
c)
left and right
d)
neither left nor right
21.

For the following reaction: H2(g) + Cl2 (g) ↔ 2HCl(g), calculate the concentration of HCl when Keq= 2.3x10-5, [H2]= 0.0056mol, [Cl2]= 0.0048mol.

a)

6.2 x 10-10 M

b)

2.5 x 10-5 M

c)

1.1 M

d)

1.2 M

22.
What are [A] and [B]?
a)
concentration of reactants
b)
concentration of products
c)
energy of reactants
d)
energy of products
23.
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]
24.

Methanol can be produced from hydrogen and carbon monoxide.

a)
b)
c)
d)
25.
Equilibrium for 2CrO42- + 2H+ → Cr2O72- + H2O. What happen when H+ ion are added to the system?
a)
Position of equilibrium will shift to left
b)
Color of system will turn from orange to yellow
c)
Kc will be higher
d)
Equilibrium will shift to right to decrease the added H+ ion