Calderglen High
Higher Chemistry Homework
Chemistry In Society –Equilibrium
1.
Chemical reactions are in a state of dynamic equilibrium only when:
A
The rate of the forward reaction equals that of the backward
reaction.
B
The concentration of reactants and products are equal.
C
The activation energies of the forward and backward reactions are
equal.
D
The reaction involves zero enthalpy change.
2.
What does the term ‘dynamic equilibrium’ mean?
3.
A(g)
+ 2B (g)
2C (g)
+ D (ℓ) ∆H negative
What will happen to the equilibrium position when:
a) the pressure is increased.
b) the temperature is increased.
c) the concentration of A is increased.
d) a substance is added which reacts with and removes B.
4.
What effect will addition of a catalyst have on:
a) the rate of the forward reaction
b) the rate of the reverse reaction
c) the time taken to reach equilibrium
d) the position of the equilibrium
5.
Increasing the pressure on the equilibrium shown below:
N2O4(g)
2NO2(g)
ΔH = +58 kJ
will cause the position of the equilibrium to
A
move to the product side
B
move to the reactant side
C
remain unchanged
D
increase
Calderglen High
Higher Chemistry Homework
Chemistry In Society –Equilibrium
6.
Decreasing the temperature in the reaction shown below
N2O4(g)
2NO2(g)
ΔH = +58 kJ
will cause the position of the equilibrium to
A
move to the product side
B
move to the reactant side
C
remain unchanged
D
increase
Questions 7 and 8 refer to the following equilibrium which exists in bromine
water.
Br2(aq) + H2O(l)
7.
2H+(aq)
+ BrO-(aq) + Br –(aq)
Addition of which of the following substances would move the equilibrium
position to the right?
8.
A
potassium nitrate
B
sodium bromide
C
sulfuric acid
D
sodium hydroxide
Addition of which of the following substances would increase the pH of
the equilibrium mixture?
A
potassium nitrate
B
sodium bromide
C
bromine
D
sodium chloride
Calderglen High
Higher Chemistry Homework
Chemistry In Society –Equilibrium
9.
Methanol can be prepared from synthesis gas as follows:
CO(g) + 2H2(g)
CH3OH(g) ΔH = -91 kJ
The formation of methanol is favoured by:
10.
A
high pressure and low temperature
B
high pressure and high temperature
C
low pressure and low temperature
D
low pressure and high temperature
In the Haber process nitrogen and hydrogen are converted into ammonia
in an exothermic equilibrium reaction. The operating conditions are 250
atmospheres pressure and a temperature of about 500 °C.
a.
Write a balanced equation for the reaction.
b.
The highest percentage yield of ammonia would be obtaine
at a low operating temperature.
Explain, therefore, the use of a temperature of about 500 °C.
c.
The reaction is not allowed to reach equilibrium.
State how this is done.
11.
Consider the following equilibrium:
N2O4(g)
(pale yellow)
2NO2(g)
ΔH positive
(dark brown)
What would be seen if the equilibrium mixture was:
a.
placed in a freezing mixture
b.
compressed?
Calderglen High
Higher Chemistry Homework
Chemistry In Society –Equilibrium
12.
2NO2(g)
N2O4(g)
ΔH = +56 kJ
Which two conditions favour the decomposition of NO2?
13.
A
low temperature, high pressure
B
high temperature, low pressure
C
low temperature, low pressure
D
high temperature, high pressure
Which of the following is likely to apply to the use of a catalyst in a
chemical reaction?
A
B
C
D
14.
Rate of forward
reaction
Rate of reverse Position of
reaction
equilibrium
Increased
Increased
Increased
unchanged
Unchanged
Increased
Decreased
unchanged
Moves right
Unchanged
Moves right
unchanged
Consider the following equilibrium:
N2(g) + O2(g)
2NO(g)
ΔH = +180 kJ
How would the equilibrium concentration of nitrogen oxide be affectd by:
a. increasing the temperature
b. decreasing the pressure
c. decreasing the concentration of oxygen