期末考
姓名：_____________
學號：______________
系別：___________
I. 單選題（每題三分）
1) Which of the following statements about quantum theory is FALSE?
a) The energy and position of an electron cannot be determined simultaneously.
b) Lower energy orbitals are filled with electrons before higher energy orbitals.
c) When filling orbitals of equal energy, two electrons occupy the same orbital
before filling a new orbital.
d) No two electrons can have the same four quantum numbers.
2) Which of the following statements is FALSE?
a) An orbital can accommodate at most two electrons.
b) The electron density at a point is proportional to 2‚ at that point.
c) The spin quantum number of an electron must be either +1/2 or -1/2.
d) A 2p orbital is more penetrating than a 2s; i.e., it has a higher electron density
near the nucleus and inside the charge cloud of a 1s orbital.
e) The 6s orbital is filled before the 4f orbital.
3) Order the intermolecular forces from weakest to strongest:
London dispersion, ionic, and hydrogen-bonding.
a) dipole-dipole, London dispersion, ionic, and hydrogen-bonding
b) London dispersion, dipole-dipole, hydrogen-bonding, ionic
dipole-dipole,
c) hydrogen-bonding, dipole-dipole, London dispersion, and ionic
d) dipole-dipole, ionic, London dispersion, and hydrogen-bonding
e) London dispersion, ionic, dipole-dipole, and hydrogen-bonding
4)
a)
b)
c)
d)
The weaker the intermolecular forces in a substance,
the greater its heat of vaporization.
the more it deviates from ideal gas behavior.
the greater its vapor pressure at a particular temperature.
the higher its melting point.
e) none of these
5)
a)
b)
c)
d)
e)
Which statement regarding water is true?
Energy must be given off to break down the crystal lattice of ice to a liquid.
Hydrogen bonds are stronger than covalent bonds.
Liquid water is less dense than solid water.
Only covalent bonds are broken when ice melts.
none of these
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6) Which of the following is the smallest hole in a closest-packed lattice of spheres?
a) trigonal
b) tetrahedral
c) cubic
d) octahedral
e) none of these
7) Which one of the following statements about solid Cu (face-centered cubic unit
cell) is FALSE?
a) It will conduct electricity.
b) There are 2 atoms per unit cell.
c) The number of atoms surrounding each Cu atom is twelve.
d) The solid has a cubic closest-packed structure.
e) The length of a face diagonal is four times the Cu radius.
8) Chromium crystallizes in a body-centered cubic structure in which the Cr atoms
are in contact along the body diagonal of the unit cell. The unit cell edge is 288.4
pm. The atomic radius of Cr is
a) 100.8 pm. b) 124.9 pm. c) 136.7 pm.
d) 177.0 pm.
e) none of these
9) Which of the following statements is true about p-type silicon?
a) It is produced by doping Si with P or As.
b) Electrons are the mobile charge carriers.
c) It does not conduct electricity as well as pure Si.
d) All the above are true.
e) none of these
10) Hvap for water is 40.7 kJ/mol. Calculate Pvap of water at 37℃. The boiling
point for water is 100℃ at 1 atm.
a)
ln(Pvap) = -(Hvap/R)(1/T) + C
R = 8.314 J/K mol
6.90 torr b) 12.4 torr c) 18.7 torr d) 25.4 torr e) 52.6 torr
11) A liquid-liquid solution is called an ideal solution if
i)
it obeys PV = nRT.
ii) it obeys Raoult's Law.
iii) solute-solute, solvent-solvent, and solute-solvent interactions
are very similar.
iv) solute-solute, solvent-solvent, and solute-solvent interactions
are quite different.
a) i, ii, iii b) i, ii, iv c) ii, iii d) ii, iv e) i, ii, iii
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12) The lattice energy of NaI is 686 kJ/mol and its heat of solution is -7.6 kJ/mol.
Calculate the hydration energy of NaI(s).
a) +15.2 b) -678 c) -694 d) +678
e) +694
13) At a given temperature, you have a mixture of benzene (Pvap = 745 torr) and
toluene (Pvap = 290. torr). The mole fraction of benzene in the solution is 0.590.
Assuming ideal behavior, calculate the mole fraction of toluene in the vapor above the
solution.
a) 0.213 b) 0.778 c) 0.641 d) 0.355
e) 0.590
14) A solution of two liquids, A and B, shows negative deviation from Raoult's law.
This means that
a) the molecules of A interact strongly with other A-type molecules.
b) the two liquids have a positive heat of solution.
c) molecules of A interact weakly, if at all, with B molecules.
d) the molecules of A hinder the strong interaction between B molecules.
e) molecules of A interact more strongly with B than A with A or B with B.
15) A 5.50-gram sample of a compound is dissolved in 250. grams of benzene. The
freezing point of this solution is 1.02 ℃ below that of pure benzene. What is the
molar mass of this compound? Kf for benzene is 5.12℃/m.
a) 22.0 g/mol
b) 110. g/mol
c) 220. g/mol
d) 44.0 g/mol
e) none of these
II. 計算問答題
1)
Chlorine gas was first prepared in 1774 by C. W. Scheele by oxidizing sodium
chloride with manganese(IV) oxide. The reaction is: (4 pts)
NaCl(aq) + H2SO4(aq) + MnO2(s)  Na2SO4(aq) + MnCl2(aq) + H2O(aq) + Cl2(g)
Balance this equation.
Oxidation: 4 NaCl  2Cl- + Cl2 + 4 Na+ + 2eReduction: 4 H+ + MnO2 +2e- + 2 SO42- Mn2+ + 2H2O + 2 SO42----------------------------------------------------------------------------------------------------4NaCl(aq)+2H2SO4(aq)+MnO2(s)  2Na2SO4(aq)+MnCl2(aq)+2H2O(aq)+Cl2(g)
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2)
Calculate the de Broglie wavelength for each of the following. (4 pts)
(a) A proton with a velocity 90.0 % of the speed of light. (mass of proton = 1.67
x 10-27 kg)
(b) A 150-g ball with a velocity of 10. m/s.
( h = 6.626 x 10-34 J.s or 6.626 x 10-34 kg.m2/s)
a = h/mv = 6.626 x 10-34 /(1.67 x 10-27 x 2.998 x 108 x 0.9) = 1.5 x 10-15 m
(b)  = h/mv =6.626 x 10-34 /(0.15 x 10) = 4.4 x 10-34 m
3) Use the following data to estimate Hfo for magnesium fluoride.
Mg(s) + F2(g)  MgF2(s)
(5 pts)
Lattice energy
-3916 kJ/mol
First ionization energy
735 kJ/mol
Second ionization energy
1445 kJ/mol
Electron affinity of F
-328 kJ/mol
Bond energy of F2
154 kJ/mol
Enthalpy of sublimation of Mg
150 kJ/mol
H = 150 kJ
H = 735 kJ
H = 1445 kJ
H = 154 kJ
H = 2 x (-328) kJ
Mg(s)  Mg(g)
Mg(g)  Mg+(g) + eMg+(g)  Mg2+(g) + eF2(g)  2F(g)
2F(g) + 2e-  2F-(g)
Mg2+(g) + F2(g)  MgF2(s)
H = -3916 kJ
---------------------------------------------------------------------------Mg(s) + F2(g)  MgF2(s)
H = -2088 kJ/mol
4) Write Lewis structures for the following molecules or ions. (20 pts)
(a) XeF4
(b) CO2
(c) N3(d) NO2+
(e) XeF2
F
F
F
Xe
Xe
F
F
(f) SO42-
N N N
O C O
(g) S2O82-
(h) XeO4
-
O N O +
(i) XeO2F2
F
(j) cis-N2F2
F
O-
O
S
O
O-
O
O
O
-
O
O
-
O
O
S
S
O O
Td
Xe
O
O
Xe
O
O
O
N N
F
F
F
4
5)
Which ones of question (4) exhibit polarity? (3 pts)
Ans: (f) SO42- (g) S2O82- (i) XeO2F2
6)
Using the molecular orbital model to describe the bonding in O2+, O2, O2-, and
O22-, predict the bond orders and the relative bond lengths for these four species.
How many unpaired electrons are present in each one? (6 pts)
O2+
O2
O2O22























Bond order 2.5
2
Unpaired e 1
2
Bond length O2+ < O2 < O2-,< O227)
(j) cis-N2F2
1.5
1
1
0
The observed osmotic pressure for a 0.10 M solution of Fe(NH4)2(SO4)2 at 25℃
is 10.8 atm. Compare the expected and experimental values for i, the van’t Hoff
factor. R = 0.08206 L.atm/K.mol
(4 pts)
 = iMRT => i = 10.8 / (0.10 x 0.08206 x 298) = 4.4 (experimental)
The expected i is 5.
8)
The solubility of nitrogen in water is 8.21 x 10-4 mol/L at 0℃ when the N2
pressure above water is 0.790 atm. Calculate the Henry’s law constant for N2 in
units of L.atm/mol for Henry’s law in the form P = kC, where C is the gas
concentration in mol/L. Calculate the solubility of N2 in water when the partial
pressure of nitrogen above water s 1.10 atm at 0℃. (4 pts)
0.790 atm = k x 8.21 x 10-4 mol/L ∴ k = 962 L.atm/mol
1.10 atm = 962 L.atm/mol x C
∴ C = 1.14 x 10 –3 mol/L
9)
What is the composition (mole fraction) of a methanol-propanol solution that has
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a vapor pressure of 174 torr at 40℃? AT 40℃, the vapor pressure of pure
methanol and pure propanol are 303 and 44.6 torr, respectively. Assume the
solution is ideal.
(4 pts)
∴
∴
174 = meth x 303 + prop x 44.6 and
prop = 1.000 - meth
174 = meth x 303 + (1.000 - meth) x 44.6
meth = 129/258 = 0.500 and prop = 0.500
10) Give the hybridiztion of each of the carbon, nitrogen and oxygen atoms in the
structure. (note: the labels of carbon atoms and lone pairs are omitted for clarity)
(4 pts)
H
sp2
sp2 sp3
O sp2
OH
sp2
sp3
H
sp2 H
sp2
H
NH
sp3 2
III. 解釋名詞(用精確的科學語言解釋，不可只翻譯，用華文或英文皆可)
1) London dispersion forces
(2 pts)
An instantaneous dipole induces a similar dipole in a neighboring atom. The force
between the two dipoles is called London dispersion force.
2)
Explain “polarity” and “polarizability”. Compare the polarity and polarizability
Cl CH3
of
and
.
(4 pts)
Polarity: the property that a molecule has separate geometric centers of positive and
negative charges.
Polarizability: The property that a molecule can be induced to become polar.
Polarity:
Polarizability:
<
Cl
CH3
>
Cl
CH3
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3)
amorphous solid
(2 pts)
A solid lacks repeating units (not crystalline).
What is “lattice point”? And draw a two-dimensional lattice for the given pattern.
(4 pts)
Lattice points are the points with the same chemical a a a a a a a a
a a a a a a a a
environment in a crystal.
a a a a a a a a
Drawing straight lines connecting lattice points forms
a a a a a a a a
a a a a a a a a
a lattice.
4)
5)
Tyndall effect
(2 pts)
Light is scattered by colloid so that one can see the light at 90o to the direction of the
beam.
6) paramagnetic and diamagnetic
(4 pts)
Materials with unpaired e are paramagnetic. Positive magnetization is induced in
magnetic field.
Materials without unpaired e- are diamagnetic. Small negative magnetization is
induced in magnetic field.
7)
Hess law
(2 pts)
Enthalpy is a state function. H of a reaction in independent of its pathway. That is
going from a particular set of reactants to a particular set of products, H is the same
whether the reaction takes place in one step or in a series of steps.
8) dipole moment
(2 pts)
Dipole moment forms when a molecule has separate geometric centers of positive and
negative charges:
9)
=exr
Ionization energy
(2 pts)
The energy required to remove electrons from a gaseous atom.
10) Pauli exclusion principle
(2 pts)
In a given atom no two electrons can have the same set of four quantum numbers.
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