AnswersMO-Physical Science A-CRShifts in Equilibrium

Shifts in Equilibrium — Unit test Answers

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Which statement best describes the reaction pathway graph for an exothermic reaction but not an endothermic reaction?

A
It has a hill in the middle that is the highest point.
B
It has a valley in the middle that is its lowest point.
C
The reactants are higher in energy than the products.
D
The products are higher in energy than the reactants.
2
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Consider the following equation in chemical equilibrium. C2H4(g) + H2(g) C2H6(g) + 137 kJ What happens to the amount of ethane (C2H6) when the temperature of the system is increased?

Question illustration
A
The amount of ethane decreases.
B
The amount of ethane increases initially and then decreases.
C
The amount of ethane increases.
D
The amount of ethane decreases initially and then increases.
3

The dissociation of a weak electrolyte is suppressed when

A
a strong electrolyte with a common ion is added to the weak electrolyte solution.
B
a strong salt is dissolved with the weak electrolyte solution.
C
a strong electrolyte with a different ion than the weak electrolyte is added.
D
the strong electrolyte solidifies in the presence of the weak electrolyte.
4

Consider the reaction pathway below.Which is true about the potential energy of the reactants in this reaction pathway?

Question illustration
A
It is greater than the potential energy of the products.
B
It is less than the potential energy of the products.
C
It is equal to the potential energy of the products.
D
It is half of the potential energy of the products.
5

A reaction occurs when solid X is placed into solution Y. As a result, the temperature of the new solution increases by 3°C. The temperature rises another 2°C when more of solid X is added to the solution. What does this indicate about the effect of adding more solid?

A
It increased the number of molecular collisions.
B
It decreased the number of molecular collisions.
C
It decreased the space between the molecules and lowered the reaction rate.
D
It increased the space between the molecules and increased the reaction rate.
6

Which energy graph represents the nonspontaneous transition of graphite into diamond?

A
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts low on the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down a short distance, and levels out.
Option A
B
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up sharply, curves down sharply, and levels out below the initial starting point.
Option B
C
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a small amount, then curves down to level out below the initial starting point.
Option C
D
A graph with Reaction progression on the horizontal axis and energy on the vertical axis. A line starts midway up the vertical axis, runs briefly parallel to the horizontal axis, slopes up a moderate amount, then curves down sharply to level out below the initial starting point.
Option D
7

Consider the reaction.When does the given chemical system reach dynamic equilibrium?

Question illustration
A
when the forward and reverse reactions stop
B
when the rate of the forward reaction is higher than the rate of the reverse reaction
C
when the concentration of the reactants is higher than the concentration of the products
D
when the rates of the forward and reverse reactions are equal
8

Consider the following reversible reaction.What is the equilibrium constant expression for the given system?

Question illustration
A
K e q equals StartFraction StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket superscript 2 over StartBracket upper C upper H subscript 3 upper O upper H EndBracket EndFraction.
Option A
B
K e q equals StartFraction StartBracket upper C upper H subscript 3 upper H upper O EndBracket over StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket superscript 2 EndFraction.
Option B
C
K e q equals StartFraction StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket over StartBracket upper C upper H subscript 3 upper O upper H EndBracket EndFraction.
Option C
D
K e q equals sart fraction StartBracket upper C upper H subscript 3 upper O StartBracket upper C upper O EndBracket StartBracket upper H 2 EndBracket EndFraction.
Option D
9

Which statement best applies collision theory to preventing a dangerous reaction from occurring?

A
Store the reactants together at a low pressure.
B
Keep all sparks or flames away from the reactants.
C
Store the reactants together at a low temperature.
D
Keep the reactants in separate containers.
10

What happens as the activation energy increases?

A
The pressure of the system decreases.
B
The kinetic energy of colliding molecules changes.
C
The reactant surface area decreases.
D
The reaction begins to slow down.
11

Consider the reaction pathway graph below.Which letter represents the activated complex?

Question illustration
A
A
B
B
C
F
D
G
12

Which will not appear in the equilibrium constant expression for the reaction below?

Question illustration
A
[H2O]
B
[C]
C
[H2]
D
[CO]
13

According to Le Chatelier’s principle, what happens when the concentration of reactants is doubled in a chemical reaction that was in equilibrium?

A
The equilibrium shifts to the right to favor the formation of products.
B
The equilibrium shifts to the left to favor the formation of reactants.
C
The equilibrium is unaffected by the increase in concentration.
D
The equilibrium is lost because the concentrations have been disturbed.
14

Consider the chemical equilibrium of a soap that is present in its aqueous solution. C17H35COONa(aq) C17H35COO–(aq) + Na+(aq)sodium stearate (soap) stearate ion What will happen if a large quantity of NaCl is added to the aqueous solution?

Question illustration
A
The equilibrium will shift to the right, favoring the dissociation of soap in aqueous solution.
B
The equilibrium will shift to the left to such an extent that it leads to the precipitation of solid soap.
C
The equilibrium will not be affected by the addition of NaCl to the solution.
D
The equilibrium will be permanently destroyed by the addition of NaCl.
15

Consider the equation below.What is the equilibrium constant expression for the given reaction?

Question illustration
A
K subscript e q equals StartFraction bracket upper C a upper O EndBracket over upper C a upper C upper O subscript 3 EndBracket EndFraction.
Option A
B
K subscript e q equals StartFraction StartBracket upper C upper O subscript 2 EndBracket StartBracket upper C a upper O EndBracket over StartBracket upper C a upper C upper O subscript 3 EndBracket EndFraction.
Option B
C
K subscript e q equals StartBracket upper C upper O subscript 2 EndBracket.
Option C
D
K subscript e q equals StartFraction 1 over StartBracket upper C upper O subscript 2 EndBracket EndFraction.
Option D
16

Consider the reaction pathway graph below. Which method would provide evidence to support the inference that this is an exothermic reaction?

Question illustration
A
add A and C
B
add E and D
C
subtract A from C
D
subtract E from D
17

Error

Answer not available
18

Consider the general reversible reaction.What is the equilibrium constant expression for the given system?

Question illustration
A
K e q equals StartFraction lowercase C StartBracket upper C EndBracket lowercase d StartBracket upper D EndBracket over lowercase A StartBracket upper A EndBracket lowercase B StartBracket upper B EndBracket EndFraction.
Option A
B
K e q equals StartFraction StartBracket upper C EndBracket StartBracket upper D EndBracket over StartBracket upper A EndBracket StartBracket upper B EndBracket EndFraction.
Option B
C
K e q equals StartFraction StartBracket upper A EndBracket superscript lower a StartBracket upper B EndBracket superscript lower b over StartBracket upper C EndBracket superscript lower c StartBracket upper D EndBracket superscript lower D EndFraction.
Option C
D
K e q equals StartFraction StartBracket upper C EndBracket superscript lower c StartBracket upper D EndBracket superscript lower D over StartBracket upper A EndBracket superscript lower a StartBracket upper B EndBracket superscript lower b EndFraction.
Option D
19

Magnesium oxide does not readily decompose into magnesium and oxygen. The reaction is shown below.MgO(s) + 601.7 kJ Mg(s) + ½O2(g)Which factor plays the most important role in allowing this reaction to occur?

Question illustration
A
temperature
B
concentration
C
pressure
D
surface area
20

Error

Answer not available

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