課程名稱︰普通化學丙
課程性質︰必修
課程教師︰黃俊誠
開課學院：生農學院
開課系所︰昆蟲 動科
考試時間︰2hr
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試題 : General Chemistry-Mid Exam
1. Assume that the reaction PF5(g) decomposes to form PF3(g) and F2(g)
with an equilibrium constant of 4.0*10(-6次) at 298K
(a)Name PF5 and PF3
(b)Write their Lewis structures
(c)Predict their molecular structures
(d)Give their expected hybird orbitals on the central atom
(e)In a particular experiment, 2.000 mol PF5(g) was placed in a 2.000-L flask.
What are their equilibrium concentrations? (Hint: K is very small)
2. Air bags are activated when a severe impact cause a steel ball to
compress a spring and electrically ignite a detonator cap. This causes
sodium azide (NaN3) to decompose explosively according to the following
reaction:
2Nan3(s) --> 2Na(s) + 3N2
What mass of NaN3(s) must be reacted to inflate an air bag to 50.0 L at
STP?
3. Calculate the pressure exerted by 0.2 mol CO2 in a 1.0000-L container at
27.0'C
a. using the ideal gae law
b. using the van der Waal equation. (a=3.59 atm.L*L/mol*mol, b=0.0427L/mol)
c. compare the results.
4. One mechanism for destrution of ozone in the upper atmosphere is
O3(g) + NO(g) --> NO2(g) + O2(g) slow
NO2(g) + O(g) --> NO(g) + O2 (g) fast
_________________________________________________
Overall reaction
a. Which species is a catalyst?
b. Which species is an intermediate?
c. Ea for the uncatalyzed reaction
O3(g) + O(g) --> 2O2(g)
is 16.0 kJ. Ea for the same reaction when catalyzed is 12kJ. What is the
ratio of the rate constant for the catalyzed reaction to that for the
uncatalyzed reaction at 300K? (Assume thet the frequency factor A is the same
for each reaction.)
d. Chlorine atoms from Freon-12 can also as a more effective catalyst for
destruction of ozone. The activeation energy for the reaction is 3kL/mol
Which is the more effective catalyst for the destruction of ozone, Cl or
NO? Please compare the rate constants between NO and Cl.
Cl + O3 --> Clo + O2 CCl2F2 --(uv)--> ClO + O2
5. Hydrogen for use in ammonia preduction is produced by the reaction:
CH4(g) + H2O(g) ---Ni(cat)(750'C)---> CO(g) + 3H2(g)
Expect whether the equilibrium will shift to right, left, or not change.
a. Gaseous carbon monoxide is added.
b. Water vapor is removed.
c. The pressure is increased by adding Argon gas.
d. The temperature is increased (the reaction is endothermic)
e. The pressure is increased by decreasing the volume of the reaction
container.
6. LiI(s) has a heat of formation of -272 kJ/mol and larrice energy of
-753 kJ/mol. The heat of sublimation of Li is 181 kJ/mol. The ionization
energy of Li(g) is 520 kJ/mol, the electron affinity of I(g) is
-295kJ/mol. Use these date to determine the bond energy of I2(g).
7. a. Write Lewis structure of the following.
SO2, IF3, CF4, IF5.
b. Which of these compounds are polar?
c. Predict these molecule structures
d. Give the expected hybind obitals for central atoms.
8. Using the molecular orbital model, write electron configurations for
the following diatomic specis and calculate the bond orders.
Which ones are paramagnetic? Which ones are diamagnetic? Place the
species in order of increasing bond length and bond energy.
a. CO+ b. CO c. CO-
9. Nomenclature
a. name each of following compounds : KOCl, HCl, Na2O2, CoBr2
b. Write the formula for each of following compounds:
Tetraphosphorus decaoxide, Magnesium carbonare, Lithium uitride,
Hypochlorous acid.
10. The rate law for the reaction 2NOCl(g) --> 2NO(g) + Cl2(g) at some
temperature is
- d{NOCl}
Rate = ______________ = k{NOCl}*{NOCL}
dt
a. If the half-life for this reaction is 5.00s when {NOCl}o = 1.000M,
calculate the value of k for this reaction.
b. How much time is required fo the concentration of NOCl to decrease
to 0.200M?
11. Calculate the average kinetic energies of H2 and O2 molecules at
1000K.
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