課程名稱︰普通化學甲
課程性質︰必修
課程教師︰林英智
開課系所︰化學系
考試時間︰2006/1/11
試題 :
1.HCl can be made by the direct reaction of H2 and Cl2 in the presence
of light. Assume that 3.0g H2 and 140g Cl2 are mixed in a 10-L flask at
28℃.(Atomic mass: Cl=35.5) Before the reaction:
(a)What are the partial pressures of the two reactant?
(b)What is the total pressure due to the gases in the flask?
After the reaction:
(c)What is the total pressure in the flask?
(d)What reactant remains in the flask?
(e)What are the partial pressures of the gases in the flask?
(f)What will be the pressure inside the flask if the temperature is
increased to 40℃?
2.Formaldehyde, CH2O, is a volatile ordanic compound thet is sometimes
released from insulation used in home construction, an it can be trapped
and build up inside the home. When this happens, people exposed to the
formaldehyde can suffer adverse healtf effects. The U.S. federal standard
for the maximum allowable concentration of formaldehyde in air is 1.0 ppbv
(parts per billion volume). ppbv is defined as
volume of component X at STP
ppbv = ───────────────× 10^9
total volume of air at STP
(a)What is the partial pressure of formaldehyde at the maximum allowable
level of 1.0 ppbv?
(b)How many molecules of formaldehyde are present in each cubic centimeter
of air when formaldehyde is present at 1.0 ppbv?
(c)How many total molecules of formaldehyde would be present in a room
with these dimensions: 15.0 m long × 10.0 m wide ×8 m high?
3.What would the ▽Hvap be for a substance whose yapor pressure doubled when
its temperature was raised from 70.0℃ to 80.0℃?
4.Metallic lithium has a body-centered cubic structure, and its unit cell
is 351pm along an edge. Lithium iodide has the same crystal lattice
surcture as sodium chloride. The cubic unit cell is 600pm along an edge.
(a)Assume that the metal atoms in lithium touch along the body diagonal of
the cubic unit cell and estimate the radius of a lithium atom.
(b)Assume that the lithium iodide the I- ions touch along the face diagonal
of the cubic unit cell and that the Li+ and I- ions touch along the cube
; calculate the radius of an I- ion and of a Li+ ion.
(c)Compare your results in parts (a) (b) for a radius of a lithium atom and
a lithium ion. Are your results reasonable? If not, how could you account
for the unexpected result? Could any of the assumption that were made be
in error?
5.If the initial concentration of the reactant in a first-order reaction is
0.50 mol/L and half-life is 400s
(a)Calculate the concentration of the reactant 1600s after initination of
the reaction.
(b)How long would it take for the concentration of the reactant to drop to
one-sixteenth its initial value?
(c)How long would it take for the concentration of the reactant to drop to
0.062 mol L-1?
6.(a)For the reaction of iodine atoms with hydrogen molecules in the gas
phase, these rate constants were obtained experimentally. Calculate the
activation energy and frequency factor for this reaction and Estimate the
rate constant of the reaction at 4000K.
2I(g) + H2(g) → 2HI(g)
────────────────
T(K) 10^-5k(L^2mol^2s^-1)
────────────────
417.9 1.12
480.7 2.60
520.1 3.96
633.2 9.38
666.8 11.50
710.3 16.10
737.9 18.54
────────────────
(b)The active energy Ea is 139.7 kJ mol^-1 for yhe gas phase reaction. HI+
CH3I → CH4 + I2. calculate the fraction of the molecules whose
collisions would be energetic enough to react at 100℃ and 1000℃.
(e^(-Ea/RT) is descrides as the fraction of molecule with sufficient
energy)
7.For the reaction
2NO(g) + Cl2(g) → 2NOCl(g)
the currently accepted mechanism is
NO + Cl2 → ← NOCl2 fast
NOCl2 + NO → 2NOCl slow
(a)What is the rate law for this mechanism?(Be sure to express it in terms
of concentrations of reactions or products of the overall reaction, not
in terns of intermediates)
(b)Suggest another mechanism that agrees with the same rate law.
8.Find the work for an isothermal expansion from a state of 4 atm and 8L to
0.6 atm for 1.2 mole of ideal gas. What is ΔH,ΔE and q for this procss?
9.Draw the label the complete MO energy level diagrams for the following
species. For each, determine the bond order, predict the stability of the
species, and predict whether the species will be paramagnetic or diamagentic
.(a) O2; (b) C2
10.The root mean square speed of a gas particle is defined as Urms=√(3RT/M)
where M is the moleculer weight and R is gas constant.(R=0.082057Latm/mol/K
or 8.3145J/mol/K). Give the equations fo the nost propable speed Ump and
the average speed Uavg. For oxygen at room temperature(25℃) calculate the
Urms,Ump, and Uavg.
11.For a con secutive reaction A → B → C, the rate constants for the first
and the second steps are k1 and k2, respectively. Derive an equaction
expressing the amount of B in terms of initial concentration of [A]0, t,
k1 and k2.
12.In a face-centered cubic packing system, raw a proper cube and denote all
sites for packing particles wite O and the octahedral hole with △. Find
the radius ratio of packing sphere and that filled in the octahedral hole.
13.Explain briefly yhe following terms:azeotrope, amorphous, triple point,
smectic liquid crystal, zone melting, perovskite.
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