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CHEMISTRY 204
HOUR EXAM I
Dr. Christine Yerkes
February 15, 2006
Spring 2006
NAME _______________________________
SIGNATURE _________________________
QUIZ TA _____________________________
Test Form A
A.
DO NOT open the exam until you are instructed to do so.
B.
The exam has 7 pages. After you are instructed to begin the exam, please check
to see that you have all 7 pages.
C.
You should also have a list of helpful information and equations and a periodic
table.
D.
The exam contains 40 questions. The point value of each question appears next
to the question number.
E.
Academic dishonesty. If cheating is observed, any students involved will receive
a zero on the exam.
INSTRUCTIONS FOR THE ANSWER SHEET.
1.
Use a soft lead pencil and make dark marks. Do NOT use a pen. Erase all changes
completely.
2.
Print your Name in the appropriate designated spaces, then blacken in the letter
boxes below each printed letter, last name first, then your first name initial.
3.
Under Network ID print your University Network ID starting from box #1, then
blacken in the corresponding letters, numbers and/or dashes.
4.
Sign your name (do not print) on the line provided. Your signature indicates that
this is your work. Print your name underneath it.
5.
Put your section number under course code:
AQA = 00001
AQF = 00005
6.
AQB = 00002
AQG = 00006
Mark only one answer for each question.
AQC = 00003
AQI = 00007
AQD = 00004
AQJ = 00008
CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 1
Questions 1-5 are true/false questions. Answer a) for true and b) for false.
1. (2) Oxygenated hemoglobin is red and deoxygenated hemoglobin is blue. This is
because oxygen is a weak-field ligand and water is a strong-field ligand for Fe2+.
2. (2) In the separation of chloroform, CHCl3 and ethanol, CH3CH2OH, by fractional
distillation, chloroform is the product collected from the condensation tube.
This is because it is the larger of the two compounds, with stronger London
Dispersion Forces.
3. (2) Tetrahedral complex ions always show a larger d orbital splitting than octahedral
complexes, with the same ligands.
4. (2) On the basis of the following vapor pressure data,
T (oC)
PH2O (torr)
PD2O(torr)
20
17.5
15.2
30
31.8
28.0
Hvap for D2O is greater than that for H2O.
5. (2) A 5.0 M NaCl solution will have a lower freezing point than expected from ideal
behavior.
6. (3) Potassium hexacyanoferrate(II) is the compound:
a) K4[Fe(CN)6]
d) K3[Fe(SCN)6]
b) KFe(SCN)4
e) K4[Fe(NCO)6]
c) K3[Fe(CN)6]
7. (3) The magnetic moment of the square planar complex, Ni(CN)42- (in Bohr
Magnetons) is:
a) 0
b) 1.4
c) 1.7
d) 2.8
e) 3.9
8. (3) Which of the following complexes is diamagnetic?
a) Ni(en)32+
b) Cu(NH3)42+
c) Ti(H2O)63+
d) Fe(CN)64- e) Co(Cl)629. (3) The empirical formula for a coordination complex is Cu NO2 . 6H2O. How many
isomers can exist with this formula? (Consider all structural and stereoisomers).
a) 1
b) 2
c) 3
d) 4
e) 6
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CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 2
Classify the following three compounds as:
10. (3) [Co(en)3]Cl2
1 unpaired electron
11. (3) K4[Fe(OH)6]
4 unpaired electrons
12. (3) [Ni(CO)6](OH)2
2 unpaired electrons
a) weak field
b) strong field
c) impossible to tell
13. (3) A compound has the empirical formula Co(NH3)5Cl3. When an aqueous solution
of this compound is mixed with excess silver nitrate, 2 moles of AgCl precipitate
per mole of compound. When excess sulfuric acid is added to this compound, no
NH4+ ions are detected in the resulting solution. The correct name for this
compound is:
a) tetramminedichlorocobalt(III)ammonium chloride
b) triamminetrichlorocobalt(III)
c) ammonium pentaamminetrichlorocobaltate(III)
d) pentaamminechlorocobalt(III) chloride
e) none of these names (a - d) are correct
14. (3) Which of the following complexes exists as a pair of optical isomers?
a)
b)
c)
d)
e)
trans-tetraamminedichlorochromium(III) chloride
cis-diamminedibromocobalt(III) chloride
trans-diamminedibromocobalt(III) chloride
trans-diamminebis(en)cobalt(III) chloride
tris(en)platinum(II) chloride
15. (3) Dilute, equimolar solutions of the following compounds are prepared. Arrange
these compounds in order of increasing freezing points of the solutions, (lowest
freezing point first).
I Na3[Co(NO2)6]
II K[Cu(en)2Cl2]
III Co(NH3)(CN)3
IV
[Cr(NH3)5Cl]Cl2
V [Pt(NH3)6]Br4
a) V < I < IV < III < II
b) I < II < III < IV < V
c) III < II < IV < I < V
d) V < I < IV < II < III
e) II < III < IV < I < V
16. (3) Which of the compounds (I - V) in the previous question would be colorless?
a) I
b) II c) III d) IV e) V
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CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 3
17. (3) The compound, [PtBrCl(NH3)2] exists as a pair of geometric isomers. Which
energy diagram, below, correctly represents this compound?
a)
b)
c)
d)
e) none of these (a-d) are correct
Hexaaquachromium(III) is a violet solution. In the next two (2) problems, predict how
each of the treatments will affect the color of this compound.
18. (2) Oxidizing the chromium, to get hexaaquachromium(VI), will give a solution that
a)
b)
c)
d)
e)
appears more green
appears more yellow
remains violet, with a less intense color
is colorless
is apparently unchanged
19. (2) Replacing some or all of the H2O with cyanide, CN-, will give a solution that
a)
b)
c)
d)
e)
appears more green
appears more yellow
remains violet, with a less intense color
is colorless
is apparently unchanged
20. (3) How many unpaired electrons in the tetrahedral FeCl4- complex?
a) 1 b) 2 c) 3` d) 4 e) 5
21. (2) Potassium metal crystallizes in the body-centered cubic structure. The number of
nearest neighbor atoms for each potassium atom in the solid is:
a) 4
b) 6
c) 8
d) 10 e) 12
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CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 4
22. (2) A compound contains two types of atoms, X and Y. Its crystal structure has a
simple cubic lattice structure, with X atoms at the corners of the unit cell and Y
atoms at the body centers. The simplest formula for this compound is:
a) X8Y
b) X2Y
c) XY
d) XY2
e) XY8
23. (2) The intermolecular forces in liquid A are considerably larger than the
intermolecular forces in liquid B. Which of the following properties is expected
to be smaller for A than for B?
a)
b)
c)
d)
e)
The vapor pressure at 20oC
The temperature at which the vapor pressure is 100 torr
The critical temperature
the heat of vaporization
the normal boiling point
24. (2) At a specified value of temperature and pressure, which of the following gases
will show the greatest deviation from the ideal gas law?
a) N2
b) NH3
c) NO
d) Ne
e) NF3
25. (2) The normal boiling point of a liquid
a) Is the temperature at which liquid and vapor are in equilibrium
b) Varies with the atmospheric pressure
c) Is the temperature at which the vapor pressure is 1 atm.
d) Is the temperature at which the vapor pressure equals external pressure
e) Is directly proportional to the molecular weight of the liquid
26. (2) The vapor pressure of a given liquid will decrease if
a) the liquid is moved to a container in which its surface area is much
smaller
b) the volume of the liquid in the container is decreased
c) the volume of the vapor phase is increased
d) the temperature is decreased
e) the number of moles of liquids is decreased
27. (3) BeCl2 crystallizes in a face-centered cubic unit cell. The ionic radius of Be2+ is 27
pm and the ionic radius of Cl- is 181 pm. With Cl- at the lattice points, which
positions will be occupied by the Be2+ ions?
a) ¼ of the tetrahedral holes
c) ½ of the tetrahedral holes
e) all of the octahedral holes
b) ¼ of the octahedral holes
d) ½ of the octahedral holes
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CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 5
28. (3) You are given a small bar of an unknown metal, X. You find the density of the
metal to be 7.14 g/cm3. An x-ray diffraction experiment measures the edge of the
unit cell as 291 pm. Assuming that the metal crystallizes in a body-centered cubic
lattice, what is X most likely to be?
a) Mg b) Ag
c) Pt
d) Cr e) none of these
Shown below is a graph of the vapor pressure of water, dichloromethane and chloroform
as a function of temperature. Use this information to answer the next 2 (two) questions.
29. (2) Identify the compound which
corresponds to each curve:
I
a)
b)
c)
d)
e)
I
H2O
CH2Cl2
CHCl3
CHCl3
CH2Cl2
II
CHCl3
CHCl3
H2O
CH2Cl2
H2O
III
CH2Cl2
H2O
CH2Cl2
H2O
CHCl3
vapor pressure (torr)
1000
II
III
800
600
400
200
20
40
60 80 100 120
temperature (oC)
30. (2) The normal boiling point of dichloromethane, CH2Cl2, is approximately:
a) 40o
b) 60o
c) 80o
d) 100o
e) can't be determined from the data
Use the phase diagram, shown below (not drawn to scale) to answer the following two (2)
questions.
31. (2) Which of the following statements (a-d) is false, ?
a)
b)
c)
d)
This substance cannot exist as a liquid above 400K
The normal boiling point is at about 100 K
The solid is more dense than the liquid
A pressure of at least 3 atm is required to condense
the gas at 400K
e) none of the statements (a-d) are false.
4
3
P
(atm)
2
1
150
400
T (K)
32. (2) When a sample of this compound, kept at 2 atm pressure and at 100 K, is placed
on a lab bench, at room temperature, it will
a) vaporize b) melt c) sublime d) condense
e) remain in the same phase
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CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 6
33. (3) An aqueous solution of acetone, CH3COCH3, is 10.00% acetone by weight. What
is the mole percentage of acetone in this solution?
a) 3.3325%
b) 5.000%
c) 10.00%
d) 11.11%
e) 17.22%
34. (3) The freezing point of a solution prepared by dissolving 20.5461 g of a nonvolatile
non-electrolyte with the empirical formula (C3H2)n in 400.0 g of benzene is
4.33oC. The freezing point of pure benzene is 5.48oC, and the Kf = 5.1 kg K/mol.
The correct molecular formula of this compound is:
a) C3H2
b) C6H4
c) C9H6
d) C15H10
e) C18H12
35. (2) The value of Kb for water is 0.51 kg K/mol. The boiling point of a 1.00 m
solution of CaCl2 should be elevated by:
a) exactly 0.51o
c) exactly 1.02o
e) exactly 1.53oC
b) somewhat less than 1.02oC
d) somewhat less than 1.53oC
36. (3) The liquids benzene (78.11 g/mol) and toluene (92.14 g/mol) form ideal solutions.
At 35oC the vapor pressure of benzene is 160.0 torr and the vapor pressure of
toluene is 50.0 torr. If 64.05 g of benzene and 106.2 g of toluene are poured into
a large container, which is covered and maintained at 35oC, what is the mole
fraction of toluene in the vapor phase when the system comes to equilibrium?
a) 0.305
b) 0.584
c) 0.624
d) 0.695
e) 0.762
37. (3) The concentration of a saturated solution of a certain non-electrolytic polypeptide
is 1.0 x 10-3 M at 25oC. The osmotic pressure, in torr, of this solution is:
a) 0.0245
b) 0.760
c) 18.6
d) 24.5
e) 156
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CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 7
Use the following information to answer the next two questions.
38. (3) At 35oC, the vapor pressure of pure X is 512 torr and of pure Y is 344 torr. A
solution of X and Y in which the mole fraction of X is 0.25 has a total vapor
pressure of 600 torr. Which of the following statements about solutions of X and
Y is true?
a) A mixture of 100.00 mL of Y and 100.00 mL of X has a volume of
200.00 mL.
b) When Y and X are mixed at 35oC, heat must be absorbed in order to
produce a solution at 35oC.
c) When Y and X are mixed at 35oC, heat is released
d) Raoult's law is obeyed by both X and Y for this solution.
e) A mixture of 100.00 mL of Y and 100 mL of X will have a volume of
significantly less than 200.00 mL
39. (2) What are possible identities of X and Y?
a)
b)
c)
d)
e)
X
CH3COCH3
CH3OH
CS2
CH3COCH3
CH3OH
Y
CH3OH
CH3COCH3
CH3COCH3
CS2
CH3CH2OH
40. (2) Which combination of compounds would give the vapor pressure diagram shown
below (Psolution = ----)?
a)
b)
c)
d)
e)
X
CH3COCH3
CH3OH
CS2
CH3COCH3
CH3OH
Y
CH3OH
CH3COCH3
CH3COCH3
CS2
CH3CH2OH
X
Y
1
XXX
Xx
0
0
1
XY
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CHEMISTRY 204
HOUR EXAM I
Spring 2006
page 8
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