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Chemistry Quiz Chapters 13-16

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 

 1. 
Which of the following is true about a system at equilibrium?
A)
The concentration(s) of the reactant(s) is equal to the concentration(s) of the product(s).
B)
No new product molecules are formed.
C)
The concentration(s) of reactant(s) is constant over time.
D)
The rate of the reverse reaction is equal to the rate of the forward reaction and both rates are equal to zero.
E)
None of the above (A-D) is true.
 
 
Consider the following equilibrium: H2(g) + I2(s) nar001-1.jpg 2HI(g)
 

 2. 
Which of the following statements about the equilibrium is false?
A)
If the system is heated, the right side is favored.
B)
This is a heterogeneous equilibrium.
C)
If the pressure on the system is increased by changing the volume, the left side is favored.
D)
Adding more H2(g) increases the equilibrium constant.
E)
Removing HI as it forms forces the equilibrium to the right.
 

 3. 
For the equilibrium system:
CO2(g) + H2(g)  mc003-1.jpg  CO(g) + H2O(g)     mc003-2.jpgH = +42 kJ/mol
K equals 1.6 at 1260 K. If 0.15 mol each of CO2, H2, CO, and H2O (all at 1260 K) were placed in a 1.0-L thermally insulated vessel that was also at 1260 K, then as the system came to equilibrium:
A)
The temperature would decrease and the mass of CO2 would increase.
B)
The temperature would decrease and the mass of CO2 would decrease.
C)
The temperature would remain constant and the mass of CO2 would increase.
D)
The temperature would increase and the mass of CO2 would increase.
E)
The temperature would increase and the mass of CO2 would decrease.
 

 4. 
Initially 2.0 moles of N2(g) and 4.0 moles of H2(g) were added to a 1.0-liter container and the following reaction then occurred:
          3H2(g) + N2(g) mc004-1.jpg 2NH3(g)
The equilibrium concentration of NH3(g) = 0.55 moles/liter at 700.°C. The value for K at 700.°C for the formation of ammonia is:
A)
1.0 ´ 10–1
B)
5.5 ´ 10–2
C)
5.5 ´ 10–3
D)
3.0 ´ 10–1
E)
none of these
 
 
Given the equation 2A(g) nar002-1.jpg 2B(g) + C(g). At a particular temperature, K = 1.6 ´ 104.
 

 5. 
Raising the pressure by lowering the volume of the container will
A)
cause [A] to increase
B)
cause [B] to increase
C)
have no effect
D)
cannot be determined
E)
none of the above
 

 6. 
Consider the endothermic reaction 2 BrCl(g) D Br2(g) + Cl2(g). What will be the effect on the equilibrium of
a)      changing the volume at constant temperature?
b)      increasing the temperature at constant volume
A)
a) equilibrium shifts towards products,       b) equilibrium shifts towards products.
B)
a) equilibrium shifts towards reactants,       b) equilibrium shifts towards products.
C)
a) equilibrium shifts towards products,       b) equilibrium shifts towards reactants.
D)
a) no change in the equilibrium,             b) equilibrium shifts towards products.
E)
a) no change in the equilibrium,             b) equilibrium shifts towards reactants.
 

 7. 
Consider the reaction, which is exothermic as written, PCl5(g) D PCl3(g) + Cl2(g).  Which of the following changes would result in the production of LESS Cl2(g)?

I.      adding PCl3(g)
II.      removing PCl3(g)
III.      reducing the volume of the container
IV.      removing PCl5(g)
V.      increasing the temperature
VI.      increasing the volume of the container
VII.      adding PCl5(g)
VIII.      reducing the temperature
IX.      adding a suitable catalyst
A)
II, III, VII, VIII
B)
I, III, IV, V
C)
I, III, IV, VIII
D)
I, V, VI, VII
E)
I, III, IV, V,  IX
 

 8. 
Consider the reaction HNO2(aq) + H2O(l) mc008-1.jpg H3O+(aq) + NO2–(aq). Which species is a conjugate base?
A)
HNO2(aq)
B)
H2O(l)
C)
H3O+(aq)
D)
NO2–(aq)
E)
two of these
 

 9. 
In which of the following reactions does the H2PO4– ion act as an acid?
A)
H3PO4 + H2O ® H3O+ + H2PO4–
B)
H2PO4– + H2O ® H3O+ + HPO42–
C)
H2PO4– + OH– ® H3PO4 + O2–
D)
The ion cannot act as an acid.
E)
Two of these.
 
 
The following three equations represent equilibria that lie far to the right.
 HNO3(aq) + CN–(aq) nar004-1.jpg HCN(aq) + NO3–(aq)
 HCN(aq) + OH–(aq) nar004-2.jpg H2O(l) + CN–(aq)
  H2O(l) + CH3O–(aq) nar004-3.jpg CH3OH(aq) + OH–(aq)
 

 10. 
Identify the strongest acid.
A)
HCN
B)
HNO3
C)
H2O
D)
OH–
E)
CH3OH
 

 11. 
For the stepwise dissociation of aqueous H3PO4, which of the following is not a conjugate acid–base pair?
A)
HPO42– and PO43–
B)
H3PO4 and H2PO4–
C)
H2PO4– and HPO42–
D)
H2PO4– and PO43–
E)
H3O+ and H2O
 

 12. 
Which of the following species is present in the greatest concentration in a 0.100 M H2SO4 solution in H2O?
A)
H3O+
B)
HSO4–
C)
H2SO4
D)
All species are in equilibrium and therefore have the same concentration.
E)
SO42–
 

 13. 
The sodium salt, NaA, of a weak acid is dissolved in water; no other substance is added. Which of these statements (to a close approximation) is true?
A)
[H+] = [A–]
B)
[H+] = [OH–]
C)
[A–] = [OH–]
D)
[HA] = [OH–]
E)
none of these
 

 14. 
Which of the following would give the highest pH when dissolved in water to form a 0.10 M solution?
A)
a strong acid
B)
a weak acid
C)
the potassium salt of a weak acid
D)
the potassium salt of a strong acid
E)
the ammonium salt of a strong acid
 
 
Select the answer that best describes an aqueous solution made from each of the following substances:
 

 15. 
solid sodium nitrate (NaNO3)
A)
acidic
B)
basic
C)
neutral
D)
cannot tell
E)
none of these (A-D)
 

 16. 
solid aluminum chloride (AlCl3)
A)
acidic
B)
basic
C)
neutral
D)
cannot tell
E)
none of these (A-D)
 

 17. 
Which of the following correctly labels the salts?
HF  (Ka = 7.2 ´ 10–4)NH3  (Kb = 1.8 ´ 10–5)HCN  (Ka = 6.2 ´ 10–10)
A)
NaCN = acidic, NH4F = basic, KCN = neutral
B)
NaCN = acidic, NH4F = neutral, KCN = basic
C)
NaCN = basic, NH4F = basic, KCN= neutral
D)
NaCN = basic, NH4F = neutral, KCN = basic
E)
NaCN = basic, NH4F = acidic, KCN = basic
 

 18. 
Which of the following is the correct order for increasing pHs for equimolar solutions of HNO3, KCl, NH4Cl, KOH, and NaC2H3O2? (Ka for HC2H3O2 is 1.80 ´ 10–5, Ka for NH4+ is 5.56 ´ 10–10).
A)
KCl, NH4Cl, HNO3, KOH, NaC2H3O2
B)
HNO3, KCl, NH4Cl, KOH, NaC2H3O2
C)
NH4Cl, HNO3, KCl, KOH, NaC2H3O2
D)
HNO3, NH4Cl, KCl, NaC2H3O2, KOH
E)
none of these
 

 19. 
Which factor listed below is most important in determining the strength of an oxyacid?
A)
the size of the molecule
B)
the ability of the molecule to change atomic orientation
C)
the identity of the central atom in the molecule
D)
the number of oxygen atoms present in the molecule
E)
none of these
 

 20. 
Which of the following would produce a basic aqueous solution?
A)
P4O10
B)
KCl
C)
CO2
D)
NH4Cl
E)
none of these
 

 21. 
Which of the following species cannot act as a Lewis base?
A)
O2–
B)
OH–
C)
CH4
D)
H2S
E)
NH3
 

 22. 
Which of the following species cannot act as a Lewis acid?
A)
K+
B)
Mg2+
C)
Al3+
D)
H+
E)
H–
 

 23. 
Which of the following statements is incorrect?
A)
A solution of ammonium chloride will have a pH less than 7.
B)
A solution of potassium bromide will have a pH of 7.
C)
A solution of cobalt(II) chloride will have a pH less than 7.
D)
Given that the Kb of ammonia is 1.8 x 10-5 and the Ka of hydrofluoric acid is 6.8 x 10-4, a solution of ammonium fluoride will have a pH of less than 7.
E)
A solution of sodium phosphate will have a pH of less than 7.
 

 24. 
Describe the pH of the following salts? NaF, NH4Cl, KI, NH4F
A)
acidic, basic, neutral, cannot tell without further information
B)
neutral, acidic, neutral, cannot tell without further information
C)
neutral, acidic, neutral, neutral
D)
basic, acidic, neutral, cannot tell without further information
E)
basic, acidic, neutral, neutral
 

 25. 
A weak acid, HF, is in solution with dissolved sodium fluoride, NaF. If HCl is added, which ion will react with the extra hydrogen ions from the HCl to keep the pH from changing?
A)
OH–
B)
Na+
C)
F–
D)
Na–
E)
none of these
 

 26. 
Which of the following solutions will be the best buffer at a pH of 9.26? (Ka for HC2H3O2 is 1.8 ´ 10–5, Kb for NH3 is 1.8 ´ 10–5).
A)
0.10 M HC2H3O2 and 0.10 M Na C2H3O2
B)
5.0 M HC2H3O2 and 5.0 M Na C2H3O2
C)
0.10 M NH3 and 0.10 M NH4Cl
D)
5.0 M NH3 and 5.0 M NH4Cl
E)
5.0 M HC2H3O2 and 5.0 M NH3
 
 
You have two buffered solutions. Buffered solution 1 consists of 5.0 M HOAc and 5.0 M NaOAc; buffered solution 2 is made of 0.050 M HOAc and 0.050 M NaOAc.
 

 27. 
How do the pHs of the buffered solutions compare?
A)
The pH of buffered solution 1 is greater than that of buffered solution 2.
B)
The pH of buffered solution 2 is greater than that of buffered solution 1.
C)
The pH of buffered solution 1 is equal to that of buffered solution 2.
D)
Cannot be determined without the Ka values.
E)
None of these (A-D).
 

 28. 
A 75.0-mL sample of 0.0650 M HCN (Ka = 6.2 ´ 10–10) is titrated with 0.65 M NaOH. What volume of 0.65 M NaOH is required to reach the stoichiometric point?
A)
750. mL
B)
7.50 mL
C)
3.75 mL
D)
75.0 mL
E)
cannot determine without knowing the pH at the stoichiometric point
 
 
Consider the following information about the diprotic acid, ascorbic acid. (H2As for short, molar mass 176.1)
H2As nar008-1.jpg HAs– + H+     pKanar008-2.jpg = 4.10 (Kanar008-3.jpg = 7.9 ´ 10–5)
HAs– nar008-4.jpg As2– + H+      pKanar008-5.jpg = 11.79 (Kanar008-6.jpg = 1.6 ´ 10–12)
The titration curve for disodium ascorbate, Na2As, with standard HCl is shown below:
nar008-7.jpg
 

 29. 
What is the pH at point III?
A)
4.10
B)
7.95
C)
11.79
D)
12.39
E)
none of these
 

 30. 
Which of the following is a major species present at point IV?
A)
H2As
B)
HAs–
C)
As2–
D)
H+
E)
none of these
 

 31. 
Assume an indicator works best when the equivalence point of a titration comes in the middle of the indicator range. Which indicator would be best for the following titration?
0.100 M HOCl (Ka = 3.5 ´ 10–8) + 0.100 M NaOH
A)
crystal violet (0.2 - 1.8)
B)
phenolphthalien (8.2 - 10.0)
C)
methyl orange (3.2 - 4.4)
D)
thymolphthalein (9.5 - 10.5)
E)
cresol red (7.0 - 8.8)
 

 32. 
In the titration of a weak acid HA with 0.100 M NaOH, the stoichiometric point is known to occur at a pH value of approximately 10. Which of the following indicator acids would be best to use to mark the endpoint of this titration?
A)
indicator A, Ka = 10–14
B)
indicator B, Ka = 10–11
C)
indicator C, Ka = 10–8
D)
indicator D, Ka = 10–6
E)
none of these
 

 33. 
In the titration of a weak acid, HA, with a sodium hydroxide solution of approximately the same concentration, the stoichiometric point occurs at pH = 9.5. Which of the following weak acid indicators would be best suited to mark the endpoint of this titration?
A)
indicator A, Ka = 10–11
B)
indicator B, Ka = 10–13
C)
indicator C, Ka = 10–9
D)
indicator D, Ka = 10–7
E)
indicator E, Ka = 10–5
 

 34. 
Which of the following mixtures would be classified as a buffer solution?
A)
50 mL of 0.100 M HCl and 50 mL of 0.100 M KCl
B)
50 mL of 0.100 M CH3COOH and 55 mL of 0.100 M NaOH
C)
50 mL of 0.100 M CH3COOH and 25 mL of 0.100 M NaOH
D)
50 mL of 0.100 M CH3COOH and 0.500 mL of 0.000100 M NaOH
E)
50 mL of 0.100 M CH3COOH and 55 mL of 0.100 M HCl
 

 35. 
Solubility Products (Ksp)
BaSO4
1.5 ´ 10–9
CoS
5.0 ´ 10–22
PbSO4
1.3 ´ 10–8
AgBr
5.0 ´ 10–13
BaCO3
1.6 ´ 10–9
Which of the following compounds is the most soluble (in moles/liter)?
A)
BaSO4
B)
CoS
C)
PbSO4
D)
AgBr
E)
BaCO3
 

 36. 
Which of the following solid salts is more soluble in 1.0 M H+ than in pure water?
A)
NaCl
B)
KCl
C)
FePO4
D)
AgCl
E)
KNO3
 

 37. 
The best explanation for the dissolution of ZnS in dilute HCl is that:
A)
The zinc ion is amphoteric.
B)
The sulfide-ion concentration is decreased by the formation of H2S.
C)
the sulfide-ion concentration is decreased by oxidation to sulfur.
D)
the zinc-ion concentration is decreased by the formation of a chloro complex.
E)
The solubility product of ZnCl2 is less than that of ZnS.
 

 38. 
Sodium chloride is added slowly to a solution that is 0.010 M in Cu+, Ag+, and Au+. The Ksp values for the chloride salts are 1.9 ´ 10–7, 1.6 ´ 10–10, and 2.0 ´ 10–13, respectively. Which compound will precipitate first?
A)
CuCl
B)
AgCl
C)
AuCl
D)
All will precipitate at the same time.
E)
Cannot be determined.
 

 39. 
A 0.012-mol sample of Na2SO4 is added to 400 mL of each of two solutions. One solution contains 1.5 ´ 10–3 M BaCl2; the other contains 1.5 ´ 10–3 M CaCl2. Given that Ksp for BaSO4 = 1.5 ´ 10–9 and Ksp for CaSO4 = 6.1 ´ 10–5:
A)
BaSO4 would precipitate but CaSO4 would not.
B)
CaSO4 would precipitate but BaSO4 would not.
C)
Both BaSO4 and CaSO4 would precipitate.
D)
Neither BaSO4 nor CaSO4 would precipitate.
E)
Not enough information is given to determine if precipitation would occur.
 

 40. 
What is the maximum concentration of carbonate ions that will precipitate BaCO3 but not MgCO3 from a solution that is mc040-1.jpg M each in Mg2+ and Ba2+? For MgCO3, Ksp = 1.0 ´ 10–15 and for BaCO3, Ksp = 2.6 ´ 10–9.
A)
mc040-2.jpg M
B)
mc040-3.jpg M
C)
mc040-4.jpg M
D)
mc040-5.jpg M
E)
None of these; MgCO3 will always precipitate before BaCO3.
 

 41. 
Which of the following solid salts should be more soluble in 1.0 M NH3 than in water?
A)
Na2CO3
B)
KCl
C)
AgBr
D)
KNO3
E)
none of these
 
 
The following questions refer to the following system: 500.0 mL of 0.020 M Mn(NO3)2 are mixed with 1.0 L of 1.0 M Na2C2O4. The oxalate ion, C2O4, acts as a ligand to form a complex ion with the Mn2+ ion with a coordination number of two.
 Mn2+ + C2O42–nar009-1.jpgMnC2O4 K1 = 7.9 ´ 103
 [Mn(C2O4)2]2–nar009-2.jpgMnC2O4 + C2O42– K2 = 1.26 ´ 10–2
 

 42. 
Find the equilibrium concentration of the [Mn(C2O4)2]2– ion.
A)
9.2 ´ 10–5 M
B)
0.01 M
C)
2.5 ´ 10–8 M
D)
1.3 ´ 10–4 M
E)
6.7 ´ 10–3 M
 

 43. 
The cation M2+ reacts with NH3 to form a series of complex ions as follows:
 M2+ + NH3mc043-1.jpgM(NH3)2+K1 = 102
 M(NH3)2+ + NH3mc043-2.jpgM(NH3)22+K2 = 103
 M(NH3)22+ + NH3mc043-3.jpgM(NH3)32+K3 = 102
A 1.0 ´ 10–3 mol sample of M(NO3)2 is added to 1.0 L of 15.0 M NH3 (Kb = 1.8 ´ 10–5). Choose the dominant species in this solution.
A)
M2+
B)
M(NH3)2+
C)
M(NH3)22+
D)
M(NH3)32+
E)
M(NO3)2
 

 44. 
Given that the Ksp for calcium fluoride [CaF2] is 3.2 x 10-15, which of the following describes a solution that is 2.00 x 10-5 M NaF and 2.00 x 10-5 M Ca(NO3)2?
A)
Q = 4 x 10-10 and there will be a precipitate formed
B)
Q = 8 x 10-10 and there will be a precipitate formed
C)
Q = 8 x 10-15 and there will be no precipitate formed
D)
Q = 1.3 x 10-13 and there will be a precipitate formed
E)
Q = 8 x 10-15 and there will be a precipitate formed
 

True/False
Indicate whether the statement is true or false.
 
 
Consider the reaction HOCl + F– nar003-1.jpg HF + OCl–
 

 1. 
Assuming that the value for K in the above reaction is greater than 1, this means that HF is a stronger acid than HOCl.
 
 
You have two buffered solutions. Buffered solution 1 consists of 5.0 M HOAc and 5.0 M NaOAc; buffered solution 2 is made of 0.050 M HOAc and 0.050 M NaOAc.
 

 2. 
Buffered solution 1 has a greater buffering capacity than buffered solution 2.
 

Short Answer
 

 1. 
Explain why 0.1 M NaCN is basic while 0.1 M NaNO3 is neutral.
 
 
Determine whether the following oxides produce an acidic, basic, or neutral solution when dissolved in water:
 

 2. 
K2O
 

 3. 
NO2
 

 4. 
Cl2O
 

 5. 
SO2
 



 
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