AP CHEM UNIT #8 TEST MC EXAM
QUESTIONS AND ANSWERS
A sample of POCl3 is placed in a closed, rigid container at 298 K and allowed to
reach equilibrium according to the equation above. Based on the value for ΔG rxn =
+490 kJ/mol, which of the following is true? - ANSWER-K=e^-490,000/8.314 x 298
<< 1 and at equilibrium POCl3 >> PCl3
A saturated aqueous solution of CdF2 is prepared. The equilibrium in the solution is
represented above. In the solution, [Cd]eq = 0.0585 M and [F]eq = 0.117 M. Some
0.90 M NaF is added to the saturated solution. Which of the following identifies the
molar solubility of CdF2 in pure water and explains the effect that the addition of NaF
has on this solubility? - ANSWER-The molar solubility of CdF2, in pure water is
0.0585 M, and adding NaF decreases this solubility because the equilibrium shifts to
favor the precipitation of some CdF2.
When colorless solutions containing Fe ions and SCN ions are combined, a deep-
red complex ion, FeSCN quickly forms, as shown in the net ionic equation above.
Which of the following explains the observation that adding a few additional crystals
of KSCN results in the red color of the solution becoming deeper? - ANSWER-The
added KSCN dissolves, causing the reaction system to respond by producing more
product to partially consume SCN and reduce its concentration.
According to the information about the dissolution of Ba(IO3)2 shown above, the
correct value of S, the molar solubility of Ba(IO3)2, can be calculated using with of
the following mathematical relationships? - ANSWER-4S^3 = 4 x 10 ^ -9 M
Shown above is information about the dissolution of AgCl in water at 298 K. In a
chemistry lab a student wants to determine the value of s, the molar solubility of
AgCl, by measuring [Ag] in a saturated solution prepared by mixing excess AgCl and
distilled water. How would the results of the experiment be attend if the student
mixed excess AgCl with tap water (in which [Cl] = 0.010 M) instead of distilled water
and the student did not account for the Cl in the tap water? - ANSWER-The value
obtained for Ksp would be too small because less AgCl would dissolve because of
the common ion effect due to the Cl already in the water
A reversible reaction is represented by the equation above. The amounts of
reactants and products at time 1 are shown in the particle diagram on the left. The
particle diagram on the right shows the amounts of reactants and products at time 2.
Based on the diagrams, what can be inferred about the relative rates of the forward
and reverse reactions between time 1 and time 2? - ANSWER-The rate of the
forward reaction is greater that the rate of the reverse reaction
In an experiment X and Y were combined in a rigid container at constant
temperature and allowed to react as shown in the equation above. The table
provides the data collected during the experiment. Based on the data, which of the
following claims is most likely correct? - ANSWER-The reaction reached equilibrium
QUESTIONS AND ANSWERS
A sample of POCl3 is placed in a closed, rigid container at 298 K and allowed to
reach equilibrium according to the equation above. Based on the value for ΔG rxn =
+490 kJ/mol, which of the following is true? - ANSWER-K=e^-490,000/8.314 x 298
<< 1 and at equilibrium POCl3 >> PCl3
A saturated aqueous solution of CdF2 is prepared. The equilibrium in the solution is
represented above. In the solution, [Cd]eq = 0.0585 M and [F]eq = 0.117 M. Some
0.90 M NaF is added to the saturated solution. Which of the following identifies the
molar solubility of CdF2 in pure water and explains the effect that the addition of NaF
has on this solubility? - ANSWER-The molar solubility of CdF2, in pure water is
0.0585 M, and adding NaF decreases this solubility because the equilibrium shifts to
favor the precipitation of some CdF2.
When colorless solutions containing Fe ions and SCN ions are combined, a deep-
red complex ion, FeSCN quickly forms, as shown in the net ionic equation above.
Which of the following explains the observation that adding a few additional crystals
of KSCN results in the red color of the solution becoming deeper? - ANSWER-The
added KSCN dissolves, causing the reaction system to respond by producing more
product to partially consume SCN and reduce its concentration.
According to the information about the dissolution of Ba(IO3)2 shown above, the
correct value of S, the molar solubility of Ba(IO3)2, can be calculated using with of
the following mathematical relationships? - ANSWER-4S^3 = 4 x 10 ^ -9 M
Shown above is information about the dissolution of AgCl in water at 298 K. In a
chemistry lab a student wants to determine the value of s, the molar solubility of
AgCl, by measuring [Ag] in a saturated solution prepared by mixing excess AgCl and
distilled water. How would the results of the experiment be attend if the student
mixed excess AgCl with tap water (in which [Cl] = 0.010 M) instead of distilled water
and the student did not account for the Cl in the tap water? - ANSWER-The value
obtained for Ksp would be too small because less AgCl would dissolve because of
the common ion effect due to the Cl already in the water
A reversible reaction is represented by the equation above. The amounts of
reactants and products at time 1 are shown in the particle diagram on the left. The
particle diagram on the right shows the amounts of reactants and products at time 2.
Based on the diagrams, what can be inferred about the relative rates of the forward
and reverse reactions between time 1 and time 2? - ANSWER-The rate of the
forward reaction is greater that the rate of the reverse reaction
In an experiment X and Y were combined in a rigid container at constant
temperature and allowed to react as shown in the equation above. The table
provides the data collected during the experiment. Based on the data, which of the
following claims is most likely correct? - ANSWER-The reaction reached equilibrium
