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WorksheetsEndothermic and Exothermic Reactions
Total questions: 81
Worksheet time: 1hrs 21mins
Which statement describes this phase change in terms of energy and entropy? Given the equation representing a phase change for carbon dioxide, CO₂(s): CO₂(s) + energy → CO₂(g)
The phase change is endothermic and entropy increases.
The phase change is endothermic and entropy decreases.
The phase change is exothermic and entropy increases.
The phase change is exothermic and entropy decreases.
Given the potential energy diagram for a reaction: Which interval on this diagram represents the difference between the potential energy of the products and the potential energy of the reactants?
1
2
3
4
Which statement correctly describes the energy changes that occur in the forward reaction?
The activation energy is 10. kJ and the reaction is endothermic.
The activation energy is 10. kJ and the reaction is exothermic.
The activation energy is 50. kJ and the reaction is endothermic.
The activation energy is 50. kJ and the reaction is exothermic.
Which information about a chemical reaction is provided by a potential energy diagram?
the oxidation states of the reactants and products
the average kinetic energy of the reactants and products
the change in solubility of the reacting substances
the energy released or absorbed during the reaction
Which arrow represents the potential energy of the reactants?
A
B
C
D
The activation energy required for a chemical reaction can be decreased by
increasing the surface area of the reactant
increasing the temperature of the reactant
adding a catalyst to the reaction
adding more reactant
A catalyst will
lower the activation energy
increase the activation energy
An example of a catalyst is a
carbohydrate
protein, specifically an enzyme
lipid
nucleic acid
What is the approximate change in enthalpy (H) for the formation of 1 mole of water? 2 H₂(g) + O₂(g) → 2 H₂O(ℓ) + 571.6 kJ
-285.8 kJ
+285.8 kJ
-571.6 kJ
+571.6 kJ
According to Reference Table I, which statement best describes the formation of HI(g)? H₂(g) + I₂(g) → 2HI(g)
It is exothermic, and heat is released.
It is exothermic, and heat is absorbed.
It is endothermic, and heat is released.
It is endothermic, and heat is absorbed.
The prefix endo- means
in
out
The prefix exo- means
in
out
In an endothermic reaction, energy is
absorbed
released
In an exothermic reaction, energy is
absorbed
released
Which arrow represents the part of the reaction most likely to be affected by the addition of a catalyst?
A
B
C
D
Which reaction would have the lowest activation energy?
the forward catalyzed reaction
the forward uncatalyzed reaction
the reverse catalyzed reaction
the reverse uncatalyzed reaction
This reaction is
endothermic
exothermic
This reaction is
endothermic
exothermic
A endothermic reaction has a
ΔH
-ΔH
A exothermic reaction has a
ΔH
-ΔH
The heat energy (ΔH) absorbed or released during the formation of products is equal to
(H_products) - (H_reactants)
(H_reactants) - (H_products)
(H_products) x (H_reactants)
H_products / H_reactants
H stands for
enthalpy
entropy
Enthalpy is a quantity equivalent to the total amount of heat in the system.
True
False
Entropy is a quantity that represents the total amount of disorder in a system.
True
False
The reaction has a forward activation energy of 20 kJ. What is the activation energy for the reverse reaction? A(g) + B(g) → C(g) + D(g) + 30 kJ
10 kJ
20 kJ
30 kJ
50 kJ
What is the heat of formation of nitrogen (II) oxide in kJ/mole? N₂(g) + O₂(g) + 182.6 kJ → 2 NO(g)
-182.6
-91.3
91.3
182.6
Which of the following best describes exothermic chemical reactions?
They never release heat.
They always release heat.
They never occur spontaneously.
They always occur spontaneously.
For a given reaction, adding a catalyst increases the rate of the reaction by
providing an alternate reaction pathway that has a higher activation energy
providing an alternate reaction pathway that has a lower activation energy
using the same reaction pathway and increasing the activation energy
using the same reaction pathway and decreasing the activation energy
If the pressure on gaseous reactants is increased, the rate of reaction is increased because there is an increase in the
activation energy
volume
concentration
heat of reaction
Which statement explains why the speed of some chemical reactions is increased when the surface area of the reactant is increased?
This change increases the density of the reactant particles.
This change increases the concentration of the reactant.
This change exposes more reactant particles to a possible collision.
This change alters the electrical conductivity of the reactant particles.
An increase in the temperature of a system at equilibrium favors the
endothermic reaction and decreases its rate
endothermic reaction and increases its rate
exothermic reaction and decreases its rate
exothermic reaction and increases its rate
What is the specific heat of water?
4.18 J/gC
0.9 J/gC
2.7 J/gC
418 J/gC
The specific heat capacity of each substance is different.
True
False
Every substance has a different specific heat capacity.
True
False
All substances have the same specific heat capacity.
True
False
The specific heat capacity of a substance is the amount of energy it takes to raise 1 gram of a substance by 1 degree Celsius.
True
False
in q = mCΔT, q represents
heat energy
mass
specific heat capacity
temperature
in q = mCΔT, m represents
heat energy
mass
specific heat capacity
temperature
in q = mCΔT, C represents
heat energy
mass
specific heat capacity
temperature
in q = mCΔT, T represents
heat energy
mass
specific heat capacity
temperature
To find ΔT, the equation is
final temperature - initial temperature
initial temperature - final temperature
final temperature + initial temperature
final temperature * initial temperature
This is a
heating curve
cooling curve
Line AB represents
solid
liquid
gas
solid to liquid
Line CD represents
solid
liquid
gas
solid to liquid
Line EF represents
solid
liquid
gas
solid to liquid
Line BC represents
solid to liquid
liquid to gas
liquid to solid
gas to liquid
Line BC represents
melting
evaporation
condensation
freezing
Line DE represents
solid to liquid
liquid to gas
gas to liquid
liquid to solid
Line DE represents
melting
evaporation
condensation
freezing
Which line segment in the graph represents boiling?
AB
BC
CD
DE
Which equation represents sublimation?
I₂ (s) → I₂ (g)
I₂ (s) → I₂ (l)
I₂ (l) → I₂ (g)
I₂ (l) → I₂ (s)
Which statement describes what happens to the energy of the particles of the sample during the time interval DE? The graph below represents the uniform heating of a sample of a substance starting as a solid below its melting point.
Average kinetic energy increases, and potential energy remains the same.
Average kinetic energy decreases, and potential energy remains the same.
Average kinetic energy remains the same, and potential energy increases.
Average kinetic energy remains the same, and potential energy decreases.
Which physical changes are endothermic?
melting and freezing
melting and evaporating
condensation and sublimation
condensation and deposition
Heating and cooling curves represent
physical changes
chemical changes
Object A at 40.0°C and object B at 80.0°C are placed in contact with each other. Which statement describes the heat flow between the objects?
Heat flows from object A to object B.
Heat flows from object B to object A.
Heat flows in both directions between the objects.
No heat flow occurs between the objects.
As temperature increases, kinetic energy
increases
decreases
As temperature increases, kinetic energy increases, and the number of collisions
increases
decreases
Reactants must collide with the proper
energy
orientation
energy and orientation
The rate of the reaction increases when the number of effective collisions
increases
decreases
Increasing the concentration of the reactants increases the rate of the reaction.
True
False
The rate of the reaction increases when the concentration of the reactants
increases
decreases
Increasing the temperature increases the rate of the reaction.
True
False
The rate of the reaction increases when the temperature
increases
decreases
Decreasing the pressure decreases the rate of the reaction.
True
False
The rate of the reaction increases when pressure
increases
decreases
Decreasing the surface area decreases the rate of the reaction.
True
False
The rate of the reaction increases when surface area
increases
decreases
The activated complex is
the highest energy point of the reaction
the lowest energy point of the reaction
What is activation energy?
the energy needed to end a chemical reaction
the energy needed to start a chemical reaction
the energy released when a chemical reaction reaches equilibrium
the energy stored in a chemical bond before the reaction begins
At equilibrium, the forward and reverse reactions are proceeding at the same rate (speed).
True
False
This represents a
heating curve
cooling curve
Line AB represents
solid
liquid
gas
gas to liquid
Line BC represents.
solid to liquid
liquid to gas
gas to liquid
liquid to solid
Line CD represents.
solid
liquid
gas
gas to liquid
Line DE represents.
gas to liquid
solid to liquid
liquid to gas
liquid to solid
Line DE represents
gas to liquid
solid to liquid
liquid to gas
liquid to solid
Line EF represents
solid
liquid
gas
gas to liquid
Line BC represents
melting
evaporation
condensation
freezing
Line DE represents
condensation
melting
evaporation
freezing
Which phase change represents an increase in entropy?
liquid to gas
liquid to solid
gas to solid
gas to liquid
Systems in nature tend to undergo changes toward
higher energy and higher entropy
higher energy and lower entropy
lower energy and higher entropy
lower energy and lower entropy
