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WorksheetsChapter 18 Equilibrium Kinetics and Thermodynamics
Total questions: 65
Worksheet time: 33mins
What is the activation energy for the reverse reaction shown below?
40 kJ
15 kJ
25 kJ
35 kJ
If the pressure on the reaction N2(g) + O2(g) ↔ 2NO(g) at equilibrium is increased,
the quantity of N2(g) decreases.
the quantity of NO(g) decreases.
the quantity of NO(g) increases.
the quantities in the system do not change.
Step 1: NO(g) + O3(g) → NO2(g) + O2(g)
Step 2: NO2(g) + O(g) → NO(g) + O2(g)
A reaction mechanism for the destruction of ozone, O3(g), is represented above. In the overall reaction, NO(g) is best described as
an inhibitor
a catalyst
a reactant
an intermediate
Which of the following factors will NOT change the concentration of ammonia (NH3) in the reaction?
N2(g) + 3H2(g) ↔ 2NH3(g) H = -kJ
Decrease in the volume of N2.
Decrease in pressure.
Increase in the amount of catalyst.
Decrease in temperature.
What is the effect of decreasing the volume on the contained gases?
N2(g) + 3H2(g) ↔ 2NH3(g) H = -X kJ
The system reacts by increasing the number of gas molecules.
The pressure on the gases decreases momentarily.
The reaction shifts toward the product gas.
Ammonia is consumed in the reaction.
If the collision lacks sufficient energy, then an activated complex
always separates into the products.
may re-form the reactants.
always evaporates.
absorbs more energy from the surroundings.
Coal dust in a mine explodes. Which of the following best explains this?
The dust was a catalyst that ignited the coal.
The coal dust has a greater surface area which increases the number of collisions
The coal dust lowers the energy barrier.
The coal dust burns with a greater enthalpy
What is the change in enthalpy for the reaction below?
4
1
2
3
In a reaction (at equilibrium) that makes more moles of gas than it consumes, what is the effect of increasing the pressure?
The answer cannot be determined.
The reaction is unchanged.
The reaction makes more reactants.
The reaction makes more products.
Zinc reacts faster in concentrated hydrochloric acid than in dilute hydrochloric acid because...
The concentration of acid has no impact on rate of reaction.
There are more collision each with a greater force in concentrated acid.
The orientation of acid molecules is proper in concentrated acid.
There are more collisions in the concentrated acid.
Why does a higher concentration make a reaction faster?
Collisions occur with greater energy only.
There are more collisions per second and the collisions are of greater energy.
There are more collisions per second only.
There are more collisions per second or the collisions are of greater energy.
What is the effect of adding more water to the following equilibrium reaction?
CO2(g) + H2O(g) ↔ H2CO3(aq)
The equilibrium is pushed in the direction of reactants.
There is no effect.
More H2CO3 is produced.
CO2 concentration increases.
What happens to a reaction at equilibrium when more reactant is added to the system?
The answer cannot be determined.
The reaction makes more products.
The reaction is unchanged.
The reaction makes more reactants.
What is the enthalpy change for the reaction below
15 kJ
50 kJ
25 kJ
10 kJ
A burning splint will burn more vigorously in pure oxygen than in air because
oxygen is a catalyst for combustion.
Their are more collisions with oxygen molecules in pure oxygen than in air.
there are more collisions with greater force of the oxygen molecules with the wood splint.
oxygen is a product of combustion.
At equilibrium,
the forward reaction rate is equal to the reverse reaction rate.
no reactions take place.
the forward reaction rate is higher than the reverse reaction rate.
the forward reaction rate is lower than the reverse reaction rate.
Which reaction has the slowest rate at any given temperature.
low energy barrier caused by an unstable activated complex.
low energy barrier caused by a stable activated complex.
high energy barrier caused by an unstable activated complex.
high energy barrier caused by a stable activated complex.
What is the activation energy for the reaction below?
4
1
2
3
The most unstable molecule in a reaction is the
the catalyst.
the activated complex.
the reactants.
the products.
Which of the changes listed below would shift the following reaction to the right?
CH4(g) + 2O2(g) ↔ 2H2O(g) + CO2(g) + heat
removal of O2
removal of CH4
increase pressure
addition of CH4
increase in temperature
Which of the changes listed below would shift the following reaction to the right?
4HCl(g) + O2(g) ↔ 2Cl2(g) + 2H2O(g) + heat
addition of Cl
decrease of pressure
increase pressure
removal of O
increase in temperature
Which of the following statements about a catalyst is true?
A catalyst speeds rate by lowering the activation barrier.
A catalyst can initiate a reaction.
A catalyst can be consumed during a reaction.
A catalyst can be changed chemically during a reaction.
If the system 2CO(g) + O2(g) ↔ 2CO2(g) has come to equilibrium and then more CO2(g) is added,
both [CO] and [O2] increase.
[CO] decreases and [O2] increases.
both [CO] and [O2] decrease.
[CO] increases and [O2] decreases.
According to Le Chatelier’s principle, when the volume is increased, the equilibrium shifts to the right. For which of the following reversible reactions is this true?
2CO(g) + O2(g) ↔ 2CO2(g)
PCl5(g) ↔ PCl3(g) Cl2(g)
S(g) + O2(g) ↔ SO2(g)
H2(g) + I2(g) ↔ 2HI(g)
A student throws wheat kernals at a bunsen burner and they land on the counter without igniting. Next, she blows wheat flour at the bunsen burner and the cloud explodes into a flame. Why?
Flour has a higher surface area which increases the number of collisions.
Flour is combustible but wheat kernals are not.
Flour has greater dispersion forces.
Grinding the seed to a flower lowers the enthalpy of the reaction.
Added heat to the reaction below will shift the reaction
forward to remove the heat
reverse to remove the heat
reverse to create heat
forward to create heat
If the concentration of reactants is higher,
the reaction rate is generally lower.
the reaction rate is generally higher.
the reaction rate is not affected.
the rate-determining step is eliminated.
Zinc reacts faster in hot hydrochloric acid than in cold hydrochloric acid because...
their are more collisions in the hot acid.
the orientation of acid molecules is proper in hot acid.
their are more collision each with a greater force in hot acid
The heat of an acid has no impact on rate of reaction.
In the reaction SO2Cl2(g) ↔ SO2(g) + Cl2(g)
heat is evolved. What happens when chlorine (Cl2) is added to the equilibrium mixture at constant volume?
The temperature of the system increases.
The temperature remains unaffected.
More chlorine is produced.
The temperature of the system decreases.
In an endothermic reaction at equilibrium, what is the effect of raising the temperature?
The answer cannot be determined.
The reaction makes more products.
The reaction is unchanged.
The reaction makes more reactants.
Pressure only has an effect on reactions taking place in a
closed container.
gas.
liquid.
solid.
If the temperature of the equilibrium system below decreases,
X + Y ↔ XY + 25 kJ
the concentrations of reactants and products do not change.
[X] increases and [XY] decreases.
[X] decreases and [XY] decreases.
[X] decreases and [XY] increases.
To be effective, a collision requires
a reaction mechanism.
sufficient energy and a favorable orientation.
sufficient energy.
a favorable orientation.
The following reaction is...
heat + O2(g) → 2 O(g)
highly spontanous and releases free energy.
weakly spontanous and releases free energy.
nonspontanous and requires free energy.
neither entropy or enthalpy is a driving force
If this has a negative value of a process, then the process occurs spontaneously.
enthalpy change, deltaH
entropy change, deltaS
free energy change, deltaG
heat of fusion
heat of vaporization
Which of the following reactions would be accompanied by the greatest decrease in entropy?
C(s) + O2(g) → CO2(g)
O2(g) + 2H2(g) → 2 H2O(g)
N2(g) + 3H2(g) → 2 NH3(g)
2 Na(s) + Cl2(g) → 2NaCl(s)
2 KClO3(s) → 2 KCl(s) + 3 O2(g)
Which of the following is true about the numerical value of Gibbs free-energy change for a spontaneous reaction?
It indicates that work must be expended.
It is negative.
It is positive for temperatures above 850C.
It is not related to enthalpy.
Entropy measures ____.
disorder
force
heat transferred
energy
In which of the following four processes is there an increase in entropy?
I. 2SO2(g) + O2(g) → 2SO3(g)
II. H2O(g) → H2O(s)
III. Hg(l) → Hg(g)
IV. H2O2(l) → H2O(l) + ½ O2(g)
I, II
all of the above
I, IV
III, IV
II, III, IV
When a rock melts inside a volcano, which of the following is true?
ΔH = +, ΔS = -
ΔH = +, ΔS = +
ΔH = - ΔS = -
ΔH = - ΔS = +
Which of the following is true about the combustion of gasoline?
Combustion has two driving forces and is highly spontaneous.
Oxygen and carbon dioxide gas are produced.
Entropy decreases.
Combustion has one driving force and is weakly spontaneous.
Which of the following statements explains why the melting of ice is a spontaneous reaction at room temperature and pressure?
Melting is accompanied by an increase of entropy.
Melting is accompanied by a decrease of energy.
Melting is accompanied by a decrease of entropy.
Melting is accompanied by an increase of energy.
The energy that is available to do work in a reaction is called ____.
entropy
enthalpyy.
heat
free energy
Which of the following describes a system that CANNOT be spontaneous.
ΔH° is negitive, and ΔS° is positive.
ΔH° is positive, and ΔS° is positive.
ΔH° is positive, and ΔS° is negative.
ΔH° is 0.0, and ΔS° is negative.
ΔH° is negitive, and ΔS° is negative.
Which of the following combinations is true when sodium chloride melts?
ΔH = 0 and ΔS = -
ΔH = - and ΔS = +
ΔH = - and ΔS = +
ΔH = + and ΔS = -
ΔH = + and ΔS = +
If ΔG for a certain reaction has a negative value at 298 K, which of the following must be true?
I. The reaction is exothermic.
II. The reaction occurs spontaneously at 298 K
III. The rate of the reaction is fast at 298 K
II and III
I and II
I, II, and III
I only
II only
In which of these systems is the entropy decreasing?
salt dissolving in water
snow melting
air escaping from a tire
a liquid cooling
rock eroding into sand
Which of the following reactions have a negative entropy change?
I. 2 H2(g) + O2(g) → 2 H2O(l)
II. 2 NH3(g) → N2(g) + 3 H2(g)
III. Ca(s) + Cl2(g) → 2 CaCl2(s)
I and III
I only
II only
I, II, and III
III only
A 2.0 L flask holds 0.40 g of helium gas. If the helium is evacuated into a larger container while the temperature is held constant, what will the effect on the entropy of the helium be?
It will remain constant as the number of helium molecules does not change.
It will decrease as the gas will be more ordered in the larger flask.
It will decrease because the molecules will collide with the sides of the larger flask less often than they did in the smaller flask.
It will increase as the gas molecules will be more dispersed in the larger flask.
It will increase as the gas molecules increase velocity to fill the larger flask.
The reaction shown in the following diagram is accompanied by a large increase in temperature. If all molecules shown are in their gaseous state, which statement accurately describes the reaction?
It is an exothermic reaction in which entropy increases.
It is an exothermic reaction in which entropy decreases.
It is an endothermic reaction in which entropy increases
It is an endothermic reaction in which entropy decreases.
It is an exothermic reaction in which entropy remains the same.
The reaction shown occurs in two elementarty steps. Which species is the intermediate?
C4H9OH
Br-
C4H9+
OH-
C4H9Br
Ozone, O3(g), protects us from the sun's UV radiation in our atmosphere. The 2 step reaction mechanism is given. Which species is the catalyst for this destructive reaction?
O3
O2
OCl
Cl
there is no catalyst in this reaction mechanism
Which letter is the activation energy of the reverse reaction?
f
b
c
d
e
What is the activation energy of the forward reaction whose energy diagram is shown?
160
80
240
180
What is the enthalpy of the forward reaction whose energy diagram is shown?
+ 80 kJ
- 80 kJ
+ 160 kJ
- 160 kJ
+ 240 kJ
For the reaction whose energy diagram is shown, the instability of which species determines the rate of reaction at any given temperature?
X2
X2 and Y2
XY
X2Y2
For the reaction given: A + B → C + D, whose energy diagram is shown, what is the amount and direction of heat flow (enthalpy) of the reaction?
10 kJ absorbed by the reaction
10 kJ released by the reaction
20 kJ absorbed by the reaction
50 kJ absorbed by the reaction
50 kJ released by the reaction
If an endothermic reaction is spontaneous at 298K, which of the following must be true for the reaction?
I. ΔG = +
II. ΔH = +
III. ΔS = +
I only
II only
I and II only
II and III only
Living systems continually take usable energy from the environment, eventually return part of it as heat, and use the rest in order to
maintin order of the system
repair damaged tissues
grow new tissues
Run cellular functions required for life
all of these
Methane burns is oxygen. What are the values of ΔH, ΔS and ΔG for this reaction?
- - +
+ + -
- - -
+ - +
- + -
Which one of the following processes results in a decrease of the entropy of the system?
boiling of water
precipitation of a salt solution
sublimation of dry ice CO2(s) CO2(g)
melting of a rock
evaporation of a lake
Which of the following will be true when a pure substance in liquid phase freezes spontaneously?
ΔG, ΔH and ΔS are all positive.
ΔG, ΔH and ΔS are all negative.
ΔG and ΔH and negative, but ΔS is positive.
ΔG and ΔS are negative, but ΔH is positive.
ΔS and ΔH are negative, but ΔG is positive.
Which of the following describes a system that CANNOT be spontaneous?
ΔH° is positive, and ΔS° is negative.
ΔH° is positive, and ΔS° is positive.
ΔH° is negative, and ΔS° is negative.
ΔH° is negative, and ΔS° is positive.
ΔH° is 0.0, and ΔS° is negative.
Which of the following is true if you cool the following reaction?
2 H2(g) + O2(g) -> 2 H2O(g) + heat
H2(g) increases
O2(g) increases
H2O(g) decreases
H2O(g) increases
Which of the following solutions shows a system in equilibrium?
