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Chemistry 162 Exam III April 22, 2015Sshowing page 22-28 out of 28

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21
Chem 162-2015 Exam III
H&P Chapter 17 = Tro Chapter 19 = Thermodynamics
Miscellaneous, including Van’t Hoff
The reaction 2SO
2
(g) + O
2
(g)
2SO
3
(g) has K = 9.1×10
2
at 800K and K = 3.2 at 1000K.
What is ∆H° for this reaction?
A
.
-1.9
10
2
kJ
B.
+1.9
10
2
kJ
C.
9.5
10
3
kJ
D.
-9.5
10
3
kJ
E.
-2.1 kJ
K
1
= 910; T
1
= 800K
K
2
= 3.2; T
2
= 1000K
ln(K
2
/K
1
) = -(∆H
o
/R)((1/T
2
) – (1/T
1
)): van’t Hoff equation
ln(3.2/910) = -(∆H
o
/8.314)((1/1000) – (1/800))
∆H
o
= -1.88 x 10
5
J = -1.88 x 10
2
kJ
A
C162s15e3v1
22
22
Chem 162-2015 Exam III
H&P Chapter 22 = Tro Chapter 23 = Transition Metals and Coordination Chemistry
Coordination Compounds
Which of the following compounds can exhibit fac-mer isomerism?
A.
[Cr(H
2
O)
4
Br
2
]
+
B.
[Fe(CO)
5
ONO]
2+
C.
[Cu(CO)
5
Br]
+
D
.
[Fe(CO)
3
(NH
3
)
3
]
3+
E.
[Fe(NH
3
)
4
(H
2
O)
2
]
2+
Octahedral fac-mer isomers:
CO
CO
H
3
N
CO
H
3
N
NH
3
Fe
Fe
H
3
N
CO
H
3
N
CO
NH
3
CO
fac-isomer
mer-isomer
NH
3
H
3
N
OH
2
Fe
H
3
N
OH
2
NH
3
fac-mer structure
With four or more identical groups it is impossible to have a fac and a mer structure,
since any fac structure will also be mer.
D
C162s15e3v1
23
23
Chem 162-2015 Exam III
H&P Chapter 17 = Tro Chapter 19 = Thermodynamics
Free Energy and Equilibria Calculations
Calculate the equilibrium constant at 298 K for the following reaction:
2HNO
3
(aq) + NO(g)
3NO
2
(g) + H
2
O(
)
G
(kJ/mol)
HNO
3
(aq)
-110.9
NO(g)
87.6
NO
2
(g)
51.3
H
2
O(
)
-237.1
A.
8.71 x 10
8
B.
0.980
C.
1.02
D
.
1.15 x 10
-9
E.
5.11 x 10
-4
ΔG
o
= Σn
p
ΔG
o
f(products)
- Σn
r
ΔG
o
f(reactants)
ΔG
o
= ((3 x 51300) + (-237100)) – ((2 x -110900) + (87600)) = 51000J
ΔG
o
= -RT ln(K)
(-51000) = (8.314 x 298 x (ln(K)))
K = 1.149 x 10
-9
D
C162s15e3v1
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24
Chem 162-2015 Exam III
H&P Chapter 16 = Tro Chapter 18 = Other Equilibria (Solubility Product, Complex Ions)
Solubility Product
A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010
M
Ca(NO
3
)
2
.
Assume no
change of volume.
K
sp
=
4.7
10
–6
for Ca(OH)
2
.
Which of the following statements is
correct
?
A.
A precipitate of calcium hydroxide will form on the bottom of the beaker.
B
.
The solution is unsaturated and no precipitate forms
C.
The concentration of calcium ions in solution is reduced by the addition of the
hydroxide ions.
D.
K
sp
for calcium nitrate is required to make meaningful predictions on this system.
E.
The presence of KOH will raise the solubility of Ca(NO
3
)
2
0.0010 M Ca(NO
3
)
2
0.015M KOH
Ca(OH)
2
→ Ca
2+
+ 2OH
-
Ca(OH)
2
Ca
2+
+
2OH
-
0.0010M
0.015M
[Ca
2+
][OH
-
]
2
= K
sp
= 4.7 x 10
-6
[0.0010][0.015]
2
= Q = 2.25 x 10
-7
2.25x10
-7
< 4.7x10
-6
; therefore, Q < K
sp
.
A.
False.
Since Q is less than K
sp
, a precipitate will not form.
B.
True.
The solution is unsaturated so no precipitate forms.
C.
False.
The concentration of calcium ions in this solution is unaffected by the
addition of hydroxide ions.
D.
False.
The K
sp
of calcium nitrate isn’t required for this calculation.
Furthermore, I
don’t think there is any such thing as a K
sp
for calcium nitrate.
E.
False.
This is an unsaturated solution at equilibrium.
That is, all of the Ca(NO
3
)
2
available has already been dissolved; therefore, there is no more to be dissolved.
B
C162s15e3v1
25
25
Chem 162-2015 Exam III
H&P Chapter 22 = Tro Chapter 23 = Transition Metals and Coordination Chemistry
Coordination Compounds
Which of the following pairs of coordination compounds or complex ions are examples of
coordination isomers?
Coordination isomers:
[MX
+
]Y
-
and [MY
+
]X
-
A.
[Fe(CO)
5
NO
2
]
2+
and [Fe(CO)
5
ONO]
2+
B.
[Fe(NH
3
)
2
(H
2
O)
4
]Cl
2
and [Fe(NH
3
)
2
(H
2
O)
4
]Br
2
C.
[Fe(NH
3
)
2
(H
2
O)
4
]Cl
2
and [Fe(NH
3
)
4
(H
2
O)
2
]Cl
2
D
.
[Cu(CO)
5
Br]Cl and [Cu(CO)
5
Cl]Br
E.
[MnCl
3
Br]
2-
and [MnClBr
3
]
2-
An isomer has the same chemical formula, but is a different compound.
B, C and E
have different chemical formulas.
Therefore, they are not isomers.
A is a linkage
isomer due to how the NO
2
groups link to the metal; D is a coordination isomer, due to
one having Br as the ligand and Cl as the counterion, while the other has Cl as the
ligand and Br as the counterion.
D
C162s15e3v1
26
26
What is the color of your exam?
A
.
White
B.
Blue
C.
Yellow
E.
Pink
C162s15e3v1
27
1.
A saturated solution of CaCO
3
A
2.
A lab technician adds 0.015 mol of KOH to
B
3.
When solid barium fluoride, BaF
2
, is placed in enough water
E
4.
A solution contains [Mg
2+
] = 0.010 M and [Ca
2+
] = 0.010 M.
Slowly,
A
5.
How many moles of PbI
2
will dissolve in 250 mL of
A
6.
AgBr(s)
Ag
+
(aq) + Br
-
(aq)
K
sp
= 5.3
10
-13
D
7.
Which of the following compounds can exhibit fac-mer isomerism?
D
8.
Which of the following pairs of coordination compounds
D
9.
Name the compound:
K
2
Ni(CN)
4
E
10.
Consider the reaction:
H
2
O(g)
H
2
O(
) at 1.00 atm and 20
o
C.
B
11.
Which of the following will have the
least
effect on whether a reaction is spontaneous?
E
12.
N
2
(g) + 3H
2
(g)
2NH
3
(g)
G
= -16.4 kJ/mol for NH
3
C
13.
A
H
(kJ mol
-
1
)
S
o
(J mol
-1
K
-1
)
N
2
O
4
(g)
9.16
304.4
NO
2
(g)
33.2
240.1
14.
What is
W
in Boltzmann's formula,
S
=
k
ln
W
?
C
15.
CO(g) + H
2
O(g)
CO
2
(g) + H
2
(g)
∆H° = -41 kJ
B
16.
Calculate the equilibrium constant at 298 K for the following reaction:
D
17.
At what temperatures will the following reaction be
nonspontaneous
C
18.
The reaction 2SO
2
(g) + O
2
(g)
2SO
3
(g) has K = 9.1×10
2
at 800K and K = 3.2 at 1000K
A
19.
When the equaon
MnO
4
+
SO
3
2–
+
H
+
Mn
2+
+
SO
4
2–
+
H
2
O is balanced
C
20.
What is the oxidation number of As in K(NH
4
)
2
AsO
4
.
6H
2
O
C
21.
E
o
(volts)
X
2+
+ 2e
-
X
-0.13
E
22.
A strip of silver metal is placed in a beaker with 1.0 M AgNO
3
.
D
23.
Cu
2+
(aq) + 2e
-
Cu(s)
E
o
= 0.34 V
E
24.
E
o
(
volts
)
B
Ag
+
(aq) + e
Ag(s)
0.80
25.
Consider the galvanic cell based on the following reaction:
E
C162s15e3v1
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