CHEM 123Exam
#1Fall 2006
For each of the following, mark your choice on the Scantron sheet in pencil.If you change your answer you must totally erase your previous mark.
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1.
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The phase diagram for
xenon has a solid-liquid curve with a positive slope. Which of the following
is true?
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A.
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Solid
xenon has a higher density than liquid xenon.
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B.
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Solid
xenon has the same density as liquid xenon.
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C.
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The
phase diagram cannot be used to predict which phase of xenon is denser.
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D.
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Freezing
xenon is an endothermic process.
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E.
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None
of these statements is true.
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2.
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Neon condenses due to
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A.
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dipole-dipole
forces.
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B.
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London
dispersion forces.
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C.
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hydrogen
bonding.
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D.
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covalent
bonding.
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E.
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intramolecular
forces.
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3.
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Ammonia's unusually high
melting point is the result of
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A.
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dipole-dipole
forces.
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B.
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London
dispersion forces.
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C.
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hydrogen
bonding.
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D.
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covalent
bonding.
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E.
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ionic
bonding.
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4.
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In hydrogen iodide __________________
are the most important intermolecular forces.
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A.
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dipole-dipole
forces
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B.
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London
dispersion forces
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C.
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hydrogen
bonding
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D.
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covalent
bonds
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E.
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polar
covalent bonds
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5.
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Which of the following
substances will have hydrogen bonds between molecules?
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A.
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(CH3)3N
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B.
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CH3-O-CH3
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C.
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CH3CH2-OH
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D.
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CH3CH2-F
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E.
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HI
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6.
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Which of the following
pairs is arranged with the particle of higher polarizability listed first?
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A.
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Se2-,
S2-
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B.
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I,
I-
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C.
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Mg2+,
Mg
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D.
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Br,
I
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E.
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none
of these choices is correct
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7.
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Which of the following
should have the highest boiling point?
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A.
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CF4
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B.
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CCl4
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C.
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CBr4
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D.
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CI4
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E.
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CH4
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8.
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Which of the following
has a boiling point which does not fit the general trend?
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A.
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NH3
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B.
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PH3
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C.
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AsH3
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D.
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SbH3
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E.
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BiH3
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9.
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When liquid bromine is
cooled to form a solid, which of the following types of solid would it
form?
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A.
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atomic
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B.
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metallic
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C.
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molecular
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D.
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ionic
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E.
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covalent
network
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10.
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When two pure substances
are mixed to form a solution
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A.
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heat
is released.
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B.
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heat
is absorbed.
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C.
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there
is an increase in entropy.
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D.
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there
is a decrease in entropy.
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E.
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entropy
is conserved.
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11.
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Potassium fluoride is
used for frosting glass. Calculate the molarity of a solution prepared
by dissolving 78.6 g of KF in enough water to produce 225 mL of solution.
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A.
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0.304
M
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B.
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0.349
M
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C.
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1.35
M
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D.
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3.29
M
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E.
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6.01
M
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12.
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Calcium nitrite is used
as a corrosion inhibitor in lubricants. What is the molality of a solution
prepared by dissolving 18.5 g of calcium nitrite in 83.5 g of distilled
water?
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A.
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0.0342
m
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B.
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0.0855
m
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C.
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0.222
m
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D.
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0.444
m
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E.
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1.68
m
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13.
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The solubility of the
oxidizing agent potassium permanganate is 7.1 g per 100.0 g of water at
25°C. What is the mole fraction of potassium permanganate in this solution?
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A.
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0.0080
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B.
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0.0086
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C.
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0.066
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D.
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0.45
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E.
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0.48
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14.
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Colligative properties
depend on
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A.
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the
chemical properties of the solute.
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B.
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the
chemical properties of the solvent.
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C.
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the
masses of the individual ions.
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D.
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the
molar mass of the solute.
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E.
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the
number of particles dissolved.
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15.
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How many moles of sulfate
ions are present in 1.0 L of 0.5 M Li2SO4?
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A.
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0.5
mol
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B.
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1.0
mol
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C.
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1.5
mol
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D.
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2.0
mol
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E.
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3.0
mol
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16. |
How many moles of sulfate
ions are present in 1.0 L of 0.5 M Li2SO4?
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A.
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0.5
mol
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B.
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1.0
mol
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C.
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1.5
mol
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D.
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2.0
mol
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E.
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3.0
mol
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17.
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Which of the following
aqueous liquids will have the lowest freezing point?
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A.
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0.5
m
C12H22O11 (sucrose)
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B.
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0.5
m
Ca(NO3)2
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C.
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0.5
m
NiSO4
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D.
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0.5
m
Li3PO4
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E.
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pure
water
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18.
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Calculate the vapor pressure
of a solution prepared by dissolving 0.500 mol of a non-volatile solute
in 275 g of hexane (
= 86.18 g/mol) at 49.6°C. P°hexane = 400.0 torr
at 49.6°C. |
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A.
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54
torr
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B.
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154
torr
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C.
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246
torr
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D.
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346
torr
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E.
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400.
torr
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19.
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Determine the freezing
point of a solution which contains 0.31 mol of sucrose in 175 g of water.
Kf
= 1.86°C/m
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A.
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3.3°C
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B.
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1.1°C
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C.
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0.0°C
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D.
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-1.1°C
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E.
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-3.3°C
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20.
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Dimethylglyoxime, DMG,
is an organic compound used to test for aqueous nickel(II) ions. A solution
prepared by dissolving 65.0 g of DMG in 375 g of ethanol boils at 80.3°C.
What is the molar mass of DMG?
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A.
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44.1
g/mol
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B.
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65.8
g/mol
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C.
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117
g/mol
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D.
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131.6
g/mol
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E.
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553
g/mol
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21.
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A 0.100 m MgSO4
solution has a freezing point of -0.23°C. What is the van't Hoff factor
for this solution?
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A.
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0.62
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B.
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1.0
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C.
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1.2
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D.
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2.0
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E.
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4.0
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22.
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Consider the following
reaction
8A(g) + 5B(g) ? 8C(g) + 6D(g)
If [C] is increasing at the rate of 4.0 mol L-1s-1,
at what rate is [B] changing? |
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A.
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-0.40
mol L-1s-1
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B.
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-2.5
mol L-1s-1
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C.
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-4.0
mol L-1s-1
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D.
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-6.4
mol L-1s-1
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E.
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none
of these choices is correct, since its rate of change must be positive
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23.
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For
the reaction
3A(g) + 2B(g) ? 2C(g) + 2D(g)
the following data was collected at constant temperature. Determine
the correct rate law for this reaction. TrialInitial
[A]Initial [B]Initial
Rate (mol/L)(mol/L)(mol/(L·min)) 10.2000.1006.00
× 10-2 20.1000.1001.50
× 10-2 30.2000.2001.20
× 10-1 40.3000.2002.70
× 10-1 |
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A.
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Rate
= k[A][B]
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B.
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Rate
= k[A][B]2
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C.
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Rate
= k[A]3[B]2
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D.
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Rate
= k[A]1.5[B]
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E.
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Rate
= k[A]2[B]
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24.
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The decomposition of hydrogen
peroxide is a first-order process with a rate constant of 1.06 ×
10-3 min-1. How long will it take for the concentration
of H2O2 to drop from 0.0200 M to 0.0120 M?
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A.
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<
1 min
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B.
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7.55
min
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C.
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481
min
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D.
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4550
min
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E.
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31,400
min
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25.
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The rate law for the reaction
3A ? 2B is rate = k[A] with a rate constant of 0.0447 hr-1.
What is the half-life of the reaction?
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A.
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0.0224
hr
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B.
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0.0645
hr
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C.
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15.5
hr
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D.
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22.4
hr
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E.
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44.7
hr
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26.
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The decomposition of SOCl2
is first-order in SOCl2. If the half-life for the reaction is
4.1 hr, how long would it take for the concentration of SOCl2
to drop from 0.36 M to 0.045 M?
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A.
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0.52
hr
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B.
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1.4
hr
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C.
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12
hr
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D.
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33
hr
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E.
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>
40 hr
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27.
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Consider the following
mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous
acid solution.
H+ + H2O2
H2O+-OH (rapid equilibrium)
H2O+-OH + Br- ? HOBr + H2O (slow) HOBr + H+ + Br- ? Br2 + H2O (fast) What is the overall reaction equation for this process? |
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A.
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2H2O+-OH
+ 2Br- ? H2O2 + Br2 + 2H2O
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B.
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2H+
+ 2Br- + H2O2 ? Br2 + 2H2O
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C.
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2H+
+ H2O2 + Br- + HOBr ? H2O+-OH
+ Br2 + H2O
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D.
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H2O+-OH
+ Br- + H+ ? Br2 + H2O
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E.
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none
of these choices is correct
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29.
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Consider the following
mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous
acid solution.
H+ + H2O2
H2O+-OH (rapid equilibrium)
H2O+-OH + Br- ? HOBr + H2O (slow) HOBr + H+ + Br- ? Br2 + H2O (fast) Which of the following rate
laws is consistent with the mechanism? |
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A.
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Rate
= k[H2O2][H+]2[Br-]
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B.
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Rate
= k [H2O+-OH][Br-]
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C.
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Rate
= k[H2O2][H+][Br-]
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D.
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Rate
= k[HOBr][H+][Br-][H2O2]
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E.
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Rate
= k[Br-]
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