課程名稱︰普通化學丙
課程性質︰必帶
課程教師︰林英智
開課學院：工學院
開課系所︰機械系
考試日期（年月日）︰2007/04/02
考試時限（分鐘）：120
是否需發放獎勵金：是
（如未明確表示，則不予發放）
試題 :
1.(a) Under appropriate coditions, molybdenum exits X rays that have a
characteristic wavelength of 0.0711nm. These X rays are used in diffraction
experiments to determine the structures of molecules. How fast would an
electron have to be moving in order to have the same wavelength as these X
rays?
(b) Carotenoids, present in all organisms capable of photosynthesis, extend
the range of light absorbed by the organism. They exhibit maximal capacity
for absorption of light in the range of 440-470nm. Calculate the energy in
kilojoules represented by absorption of an Avogadro's number of photons of
wavelength 455nm.
2.(a)Write the electron cofiguration for Li, and estimate the effective
nuclear charge experienced by the valence electron.
(b)The energy of an electron in a one-electron atom or ion equals, where Z
is the nuclear charge and n is the principal quantum number of the electron.
Estimate the first ionization energy of Li.
(c)Compare the result of your calculation with the value reported in the
following, and explain the difference.
(d)What value of the effective nuclear charge gives the proper value for
the ionization energy? Does this agree with your explanation in (c)?
3.In the vapor phase, BeCl2 exists as a discrete molecule.(a)Draw the Lewis
structure of this molecule, using only single bonds. Does this Lewis
structure satisfy the octet rule? (b)wat other resonance form are possible
that satisfy the octet rule? (c)Using formal charges, select the resonance
form from among all the Lewis structure that is most important in describing
BeCl2.
4.(a)Place the following gases in order of increasing average molecular speed
at 25'c:He, HBr, SO2, NF3, CO. (b)Calculate the rms speed of NF3and SO2
molecules at 25'C.
5.A gaseous mixture of O2 and Kr has a density of 1.104 g/L at 435 torr and
300K. What is the mole percent O2 in the mixture?
6.An element crystallizes in a body-centered cubic lattice. The edge of the
unit cell is 0.286nm, and the density of the crystal is 7.92g/cm^3. Calculate
the atomic weight of the element.
7.(a)What is the probability of finding an electron on the internuclear axis
if the electron occupies a pi molecular orbital? (b)For a homonuclear
diatomic molecule, what similarities and differences are there between the
pi2p atomic orbitals? (c)Why are the pi2p MOs lower in energy than the pi2p*
Mos?
8.Using the molecular orbital model to describe the bonding in F2+, F2, F2-
,predict the bond orders and the relative bond lengths for these three
species. How many unpaired electrons are present in each species?
9.For a simple cubic array, solve for the volume of an interior sphere
(cubic hole) in terms of the radius of a sphere in the aray.
10. The treatment of a particle in a one-dimensional box can be extended to a
two-dimensional box of dimensions Lx and Ly yielding the following expression
for energy(有個公式太難打了) The two quantum numbers independently can assume
only integer values. Consider an electron confined to a two-dimensional box
that is 8.00nm in the x direction and 5.00nm in the y direction.(a)What
are the quantum numbers for the first three allowed energy levels? (b)
calculate the wavelength of light necesary to promote an electron from the
first excited state to the second excited state.
11. The phase diagram of liquid and gas of amixture is shown below. Using the
phase diagram,(a) Determine the relative mass of gas and liquid and their mass
fraction at 120'C by heating a 1kg mixture with X=0.3 (b) Give the heating
curve of this mixture from 40'C to 180'C. At each bending point specify the
temperature.
12. Use both molecular orbital theory and valence bond theory to interprent
the paramagnetism of oxygen molecules O2.
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