CHEM 1332 SUMMER 2005
TEST 3 VERSION 1
NO CHEATING!
BUBBLE IN “1” IN THE P COLUMN TO GET YOUR GRADE POSTED!!!!! [the only way you’ll find out how you did!]
1.
Calculate the pH when 50.0 mL of a 0.200 M solution of CH3COOH(aq) is titrated with 50.0 mL of a 0.100 M KOH(aq) solution.
(Ka of CH3COOH is 1.8 x 10-5)
(A)
1.8 x 10-5
2.
Which of the following statements is incorrect?
(A)
(B)
(C)
(D)
(E)
When hydrofluoric acid (Ka = 7.2 x 10-4) is titrated with lithium hydroxide, the pH at the equivalence point will be greater than 7.
When ammonia (Kb = 1.8 x 10-5) is titrated with nitric acid, the pH at the equivalence point will be less than 7.
When lithium hydroxide is titrated with nitric acid, the pH at the equivalence point will be equal to 7.
When ammonia is titrated with hydrofluoric acid, the pH at the equivalence point will be greater than 7.
When polyprotic acids are titrated with a strong base, there is more than one equivalence point.
3.
Calculate the pH of a solution that is formed when 25.0 mL of 0.24 M ammonia (Kb = 1.8 x 10-5) is mixed with 25.0 mL of 0.24 M
hydrobromic acid.
(A)
2.83
4.
Calculate the pH of a solution that is formed when 25.0 mL of 0.24 M ammonia (Kb = 1.8 x 10-5) is mixed with 25.0 mL of 0.20 M
ammonium chloride.
(A)
2.83
5.
Which of the following mixtures would be described as a buffer solution?
(A)
(B)
(C)
(D)
(E)
25.0 mL of 0.1 M NaOH and 25.0 mL of 0.1 M HCl
25.0 mL of 0.1 M CH3COOH and 25.0 mL of 0.1 M HCl
25.0 mL of 0.1 M NaOH and 25.0 mL of 0.1 M CH3COOH
25.0 mL of 0.05 M NaOH and 25.0 mL of 0.1 M CH3COOH
25.0 mL of 0.000005 M NaOH and 25.0 mL of 0.1 M CH3COOH
(B)
(B)
(B)
2.72
5.09
4.67
(C)
(C)
(C)
4.74
5.67
9.17
1
(D)
(D)
(D)
9.26
8.91
9.33
(E)
(E)
(E)
11.28
11.17
11.17
6.
Calculate the solubility (in mol/L) of lanthanum iodate (La(IO3)3) for which the Ksp = 6.1 x 10-12 at 25 °C.
(A)
3.74 x 10-44
7.
Calculate the solubility of lead(II)fluoride (Ksp = 3.6 x 10-8) in mol/L in a solution that is 0.200 M MgF2.
(A)
9.00 x 10-8
8.
Which of the following solutions will not form a precipitate given the Ksp values:
Fe(OH)2 is 7.9 x 10-16
(B)
(B)
2.47 x 10-6
1.80 x 10-7
CaF2 is 3.9 x 10-11
(C)
(C)
1.15 x 10-4
2.25 x 10-7
AgCl is 1.8 x 10-10
(D)
(D)
6.89 x 10-4
9.00 x 10-7
A solution that is 1.00 x 10-5 FeCl2 and 1.00 x 10-5 NaOH
A solution that is 1.0 x 10-3 CaCl2 and 2.0 x 10-4 LiF
A solution that is 2 x 10-5 AgNO3 and 1 x 10-5 KCl
A solution that is 2 x 10-4 MgCl2 and 2.00 x 10-4 Na2CO3
A solution that is 5 x 10-2 NaNO3 and 6 x 10-3 (NH4)2SO4
9.
Which of the following compounds will NOT be more soluble in acidic aqueous solution than in "pure" water?
(A)
AgOH
10.
Which of the following pairs has the species with higher entropy listed first?
(A)
(B)
(C)
(D)
(E)
H2O(s), H2O(l)
CO2(g) at 25 °C and 1 atm, CO(g) at 25 °C and 1 atm
CO(g) at 25 °C and 2 atm, CO(g) at 25 °C and 1 atm
CO(g) at 25 °C and 1 atm, CO(g) at 50 °C and 1 atm
NaCl(s), NaCl(aq)
AgCl
(C)
AgF
2
2.24 x 10-3
(E)
2.08 x 10-3
(E)
Ag2CO3
MgCO3 is 3.5 x 10-8
(A)
(B)
(C)
(D)
(E)
(B)
(E)
(D)
Ag3PO4
11.
Calculate the value of ∆G° in kJ/mol at 30.0 °C for the reaction, NO2 + 7/2 H2 ∆ 2 H2O + NH3, given the values of S° and ∆Hf°
below:
Compound
∆Hf° (kJ/mol)
S° (J/mol K)
NO2
-70
220
H2
0
160
(B)
H2O
-280
180
(A)
62,890
12.
If a process is exothermic and not spontaneous, then what must be true?
(A)
∆H = 0
13.
Given the values of ∆G° given for the reactions below, determine the value of ∆G° for the reaction, H2O(l) + SO3(g) ∆ H2SO4(aq)
(B)
5,560
NH3
-250
210
(C)
∆S < 0
(C)
-5,560
∆S > 0
(D)
-676
(E)
-804
(D)
∆H > 0
(E)
∆G = 0
S(s) + O2(g) ∆ SO2(g)
∆G° = -100 kJ
∆G° = -300 kJ
2 S(s) + 3 O2(g) ∆ 2 SO3(g)
∆G° = -400 kJ
2 H2(g) + O2(g) ∆ 2 H2O(l)
∆G° = -100 kJ
2 SO2(g) + O2(g) ∆ 2 SO3(g)
∆G° = 600 kJ
H2SO4(aq) ∆ H2(g) + 2 O2(g) + S(s)
(A)
-300 kJ
(B)
14.
For CdO(s) + SO3(g) ∆ CdSO4(s) ∆H0 = -279.4 kJ and ∆S0 = -118.4 J/ K. What is the temperature at which Keq is 1.0 x 104?
(A)
2163 K
15.
Given that ∆Gf° for NH3(g) is –16.48 kJ/mol, calculate K at 25 °C for the reaction,
(B)
300 kJ
7223 K
(C)
100 kJ
(C)
(D)
1433 K
(D)
250 kJ
(E)
-250 kJ
1983 K
(E)
3.46 K
1.7 x 10-6
(E)
0.997
2 NH3(g) ∆ N2(g) + 3 H2(g)
(A)
5.9 x 105
(B)
1.007
(C)
1.3 x 10-3
3
(D)
16.
For the reaction, X + Y ∆ A + B, ∆G° = -1324 kJ. Which of the following statements cannot be concluded concerning this reaction?
(A)
(C)
(E)
the equilibrium constant is greater than 1
the reaction is thermodynamically favorable
the products are more stable than the reactants
17.
When the following equation (in aqueous acidic solution) is balanced using the smallest possible integers, what is the coefficient of
water? Cl-(aq) + Cr2O72-(aq) → Cl2(g) + Cr3+(aq)
(A)
2
18.
When the following equation (in aqueous basic solution) is balanced using the smallest possible integers, what is the coefficient of
water? N2H4(aq) + Ag2O(s) → N2(g) + Ag(s)
(A)
1
19.
Given the following values of E° in V, determine the best reducing agent of those listed in the answers.
(B)
(B)
4
2
(B)
(D)
(C)
(C)
the reaction will proceed rapidly from left to right
the reaction is spontaneous as written
5
(D)
3
(D)
7
4
(E)
14
(E)
6
(E)
K+(aq)
F2(g) + 2 e- ∆ 2 F-(aq) 2.87
Cl2(g) + 2 e- ∆ 2 Cl-(aq)
Na+(aq) + e- ∆ Na(s)
K+(aq) + e- ∆ K(s)
1.36
-2.71
-2.93
(A)
F2(g)
(B)
20.
Given that E°cell is 2.26 V for the reaction, Al(s) + 3 Fe3+(aq) ∆ Al3+(aq) + 3 Fe2+(aq), and that E°red for Fe3+ is +0.60 V, what is E°red
for Al3+(aq)?
(A)
+1.66 V
(B)
F-(aq)
-2.86 V
(C)
(C)
Na+(aq)
+0.46 V
4
(D)
(D)
Na(s)
+2.86 V
(E)
-1.66 V
CHEM 1332 SUMMER 2005
TEST 3 VERSION 2
NO CHEATING!
BUBBLE IN “1” IN THE P COLUMN TO GET YOUR GRADE POSTED!!!!! [the only way you’ll find out how you did!]
1.
For the reaction, X + Y ∆ A + B, ∆G° = -1324 kJ. Which of the following statements cannot be concluded concerning this reaction?
(A)
(C)
(E)
the equilibrium constant is greater than 1
the reaction is thermodynamically favorable
the products are more stable than the reactants
2.
When the following equation (in aqueous acidic solution) is balanced using the smallest possible integers, what is the coefficient of
water? Cl-(aq) + Cr2O72-(aq) → Cl2(g) + Cr3+(aq)
(A)
2
3.
When the following equation (in aqueous basic solution) is balanced using the smallest possible integers, what is the coefficient of
water? N2H4(aq) + Ag2O(s) → N2(g) + Ag(s)
(A)
1
4.
Given the following values of E° in V, determine the best reducing agent of those listed in the answers.
(B)
(B)
4
2
(B)
(D)
(C)
(C)
the reaction will proceed rapidly from left to right
the reaction is spontaneous as written
5
(D)
3
(D)
7
4
(E)
14
(E)
6
(E)
K+(aq)
F2(g) + 2 e- ∆ 2 F-(aq) 2.87
Cl2(g) + 2 e- ∆ 2 Cl-(aq)
Na+(aq) + e- ∆ Na(s)
K+(aq) + e- ∆ K(s)
1.36
-2.71
-2.93
(A)
F2(g)
(B)
5.
Given that E°cell is 2.26 V for the reaction, Al(s) + 3 Fe3+(aq) ∆ Al3+(aq) + 3 Fe2+(aq), and that E°red for Fe3+ is +0.60 V, what is E°red
for Al3+(aq)?
(A)
+1.66 V
(B)
F-(aq)
-2.86 V
(C)
(C)
Na+(aq)
+0.46 V
1
(D)
(D)
Na(s)
+2.86 V
(E)
-1.66 V
6.
Calculate the value of ∆G° in kJ/mol at 30.0 °C for the reaction, NO2 + 7/2 H2 ∆ 2 H2O + NH3, given the values of S° and ∆Hf°
below:
Compound
∆Hf° (kJ/mol)
S° (J/mol K)
NO2
-70
220
H2
0
160
(B)
H2O
-280
180
(A)
62,890
7.
If a process is exothermic and not spontaneous, then what must be true?
(A)
∆H = 0
8.
Given the values of ∆G° given for the reactions below, determine the value of ∆G° for the reaction, H2O(l) + SO3(g) ∆ H2SO4(aq)
(B)
5,560
NH3
-250
210
(C)
∆S < 0
(C)
-5,560
∆S > 0
(D)
-676
(E)
-804
(D)
∆H > 0
(E)
∆G = 0
S(s) + O2(g) ∆ SO2(g)
∆G° = -100 kJ
∆G° = -300 kJ
2 S(s) + 3 O2(g) ∆ 2 SO3(g)
∆G° = -400 kJ
2 H2(g) + O2(g) ∆ 2 H2O(l)
∆G° = -100 kJ
2 SO2(g) + O2(g) ∆ 2 SO3(g)
∆G° = 600 kJ
H2SO4(aq) ∆ H2(g) + 2 O2(g) + S(s)
(A)
-300 kJ
(B)
9.
For CdO(s) + SO3(g) ∆ CdSO4(s) ∆H0 = -279.4 kJ and ∆S0 = -118.4 J/ K. What is the temperature at which Keq is 1.0 x 104?
(A)
2163 K
10.
Given that ∆Gf° for NH3(g) is –16.48 kJ/mol, calculate K at 25 °C for the reaction,
(B)
300 kJ
7223 K
(C)
100 kJ
(C)
(D)
1433 K
(D)
250 kJ
(E)
-250 kJ
1983 K
(E)
3.46 K
1.7 x 10-6
(E)
0.997
2 NH3(g) ∆ N2(g) + 3 H2(g)
(A)
5.9 x 105
(B)
1.007
(C)
1.3 x 10-3
2
(D)
11.
Calculate the solubility (in mol/L) of lanthanum iodate (La(IO3)3) for which the Ksp = 6.1 x 10-12 at 25 °C.
(A)
3.74 x 10-44
12.
Calculate the solubility of lead(II)fluoride (Ksp = 3.6 x 10-8) in mol/L in a solution that is 0.200 M MgF2.
(A)
9.00 x 10-8
13.
Which of the following solutions will not form a precipitate given the Ksp values:
Fe(OH)2 is 7.9 x 10-16
(B)
(B)
2.47 x 10-6
1.80 x 10-7
CaF2 is 3.9 x 10-11
(C)
(C)
1.15 x 10-4
2.25 x 10-7
AgCl is 1.8 x 10-10
(D)
(D)
6.89 x 10-4
9.00 x 10-7
(E)
2.24 x 10-3
(E)
2.08 x 10-3
(E)
Ag2CO3
MgCO3 is 3.5 x 10-8
(A)
(B)
(C)
(D)
(E)
A solution that is 1.00 x 10-5 FeCl2 and 1.00 x 10-5 NaOH
A solution that is 1.0 x 10-3 CaCl2 and 2.0 x 10-4 LiF
A solution that is 2 x 10-5 AgNO3 and 1 x 10-5 KCl
A solution that is 2 x 10-4 MgCl2 and 2.00 x 10-4 Na2CO3
A solution that is 5 x 10-2 NaNO3 and 6 x 10-3 (NH4)2SO4
14.
Which of the following compounds will NOT be more soluble in acidic aqueous solution than in "pure" water?
(A)
AgOH
15.
Which of the following pairs has the species with higher entropy listed first?
(A)
(B)
(C)
(D)
(E)
H2O(s), H2O(l)
CO2(g) at 25 °C and 1 atm, CO(g) at 25 °C and 1 atm
CO(g) at 25 °C and 2 atm, CO(g) at 25 °C and 1 atm
CO(g) at 25 °C and 1 atm, CO(g) at 50 °C and 1 atm
NaCl(s), NaCl(aq)
16.
Calculate the pH when 50.0 mL of a 0.200 M solution of CH3COOH(aq) is titrated with 50.0 mL of a 0.100 M KOH(aq) solution.
(Ka of CH3COOH is 1.8 x 10-5)
(A)
1.8 x 10-5
(B)
(B)
AgCl
2.72
(C)
(C)
AgF
4.74
3
(D)
(D)
Ag3PO4
9.26
(E)
11.28
17.
Which of the following statements is incorrect?
(A)
(B)
(C)
(D)
(E)
When hydrofluoric acid (Ka = 7.2 x 10-4) is titrated with lithium hydroxide, the pH at the equivalence point will be greater than 7.
When ammonia (Kb = 1.8 x 10-5) is titrated with nitric acid, the pH at the equivalence point will be less than 7.
When lithium hydroxide is titrated with nitric acid, the pH at the equivalence point will be equal to 7.
When ammonia is titrated with hydrofluoric acid, the pH at the equivalence point will be greater than 7.
When polyprotic acids are titrated with a strong base, there is more than one equivalence point.
18.
Calculate the pH of a solution that is formed when 25.0 mL of 0.24 M ammonia (Kb = 1.8 x 10-5) is mixed with 25.0 mL of 0.24 M
hydrobromic acid.
(A)
2.83
19.
Calculate the pH of a solution that is formed when 25.0 mL of 0.24 M ammonia (Kb = 1.8 x 10-5) is mixed with 25.0 mL of 0.20 M
ammonium chloride.
(A)
2.83
20.
Which of the following mixtures would be described as a buffer solution?
(A)
(B)
(C)
(D)
(E)
25.0 mL of 0.1 M NaOH and 25.0 mL of 0.1 M HCl
25.0 mL of 0.1 M CH3COOH and 25.0 mL of 0.1 M HCl
25.0 mL of 0.1 M NaOH and 25.0 mL of 0.1 M CH3COOH
25.0 mL of 0.05 M NaOH and 25.0 mL of 0.1 M CH3COOH
25.0 mL of 0.000005 M NaOH and 25.0 mL of 0.1 M CH3COOH
(B)
(B)
5.09
4.67
(C)
(C)
5.67
9.17
4
(D)
(D)
8.91
9.33
(E)
(E)
11.17
11.17