課程名稱︰普通化學丙
課程性質︰必修
課程教師︰彭旭明
開課學院：醫學院
開課系所︰醫學系
考試日期（年月日）︰96/1/17
考試時限（分鐘）：120+10(10是助教後來加的)
是否需發放獎勵金：是^^
（如未明確表示，則不予發放）
試題 :
1.The phase diagram for carbon, shown here, indicates the extreme conditions
that are needed to form diamonds from graphite. (a)At 2000K, what is the
minimum pressure needed before graphite changes into diamond? (b)What is the
minimum temperature at which liquid carbon can exist at pressure 10000 atm?
(c)At what pressure does graphite melt at 3000K? (d)What are the triple
points in the diagram?(寫座標即可) (e)Are diamonds stable under normal
conditions? If not, why is that people can wear them without having to
compress and heat them?(10%)
圖為碳的相圖，可參考Atkins的Chemical Principles P.318 習題8.18的圖
2.(a)A solution of a nonvolatile solute in benzene has a vapor pressure of 740
Torr at 80.1℃. What is the osmotic pressure of this solution at 20℃?
Assume that the density of the solution is the same as that of benzene,
0.88g/cm^3. (b)The freezing point of a different benzene solution was 5.4℃.
Determine the osmotic pressure of the solution at 10℃. (c)Determine the
height to which osmosis will force the solution to rise in part(b). (The
density of mercury is 13.6g/cm^3; Benzene: M.W. 78.11, b.p. 80.1℃,
f.p. 5.5℃, kb 2.53 kf 5.12) (9%)
3.Let α be the fraction of PCl5 molecules that have decomposed to PCl3 and
Cl2 in the reaction PCl5(g) <-> PCl3(g)+Cl2(g) in a constant-volume
container; then the amount of PCl5 at equilibrium is n(1-α), where n is
the amount present initially. Derive an equation for K in terms of α and
the total pressure P, and solve it for α in terms of P. Calculate the
fraction decomposed at 556K, at which temperature K=4.96, and the total
pressure is (a)0.50atm; (b) 1.00atm. (6%)
4.(a)Calculate the value of the equilibrium constant, K, for the reaction
O2(g)+O(g)<->O3(g), given that
NO2(g)<->NO(g)+O(g) K=6.8*10^-49
O3(g)+NO(g)<->NO2(g)+O2(g) K=5.8*10^-34
(b)the initial total pressure of an equimolar mixture of the reactions is
4.0atm. What are the equilibrium partial pressure of the reactants and
products?(6%)
5.Heavy water is deuterium oxide, D2O. The standard reacition free energy for
the autoprotolysi of pure deuterium oxide is +84.8kj/mole at 298K. (a)If pD
is defines analogously to pH, what is the pD of pure D2O at 298K? (b)Does pD
increase or decrease as the terperature is raise?(6%)
6.The partial pressure of CO2(g) in air saturated with water vapor at 25℃ and
1.00atm is 3.04*10^-4atm. Henry's constant for CO2 in water is 2.3*10^-2
mol/L*atm; and, for carbonic acid, pKa1=6.37. Calculate the pf of "normal"
rainwater.(6%)
7.A buffer solution containing equal amounts of acetic acid and sodium acetate
is prepared. What concentration of the buffer must be prepared to prevent a
change in the pHby more than 0.20 pH units ahter the addition of 1.00mL of
6.00M HCl(aq) to 100.0mL of the buffer solution?(CH3COOH, Ka=1.8*10^-5) (6%)
8.The fluorid ions in drinking water convert to hydroxyapatite, Ca5(PO4)3OH,
of teeth in fluorapatite, Ca5(PO4)3F. The Ksp values of the two compounds
are 1.0*10^-36 and 1.0*10^-60, respectively.
(a)What are the molar solubilities of each substance? The solubility
equilibria to consider are
2+ 3- -
Ca5(PO4)3OH(s) <-> 5Ca (aq)+3PO4 (aq)+OH (aq)
2+ 3- -
Ca5(PO4)3F(s) <-> 5Ca (aq)+3PO4 (aq)+F (aq)
(b)What is the standard reaction free energy for te conversion of
hydroxyapatite into fluorapatite?(6%)
9.A kidney stone is a small hard mass, usually consisting of mineral salts
from urine, that forms in a kidney. Oxalate minerals are a common
constitutent of kidney stones. (a)What is the molar solubility of calcium
oxalate, CaC2O4(pKsp=8.59) in water? (b)If the concentration of Mg2+ ion in
fluids discharged from kidney is 0.02mol/L and the concentration of oxalate
2-
ion C2O4 , is 0.035mol/L, will magnesium oxalate(pKsp=4.07) precipitate?(6%)
10.(a)What is the approximate chemical formula of rust?(寫出兩種) (b)What is
the oxidizing agent in the formation of rust? (c)How does the presence of
salt accelerate the rusting process?(6%)
11.Suppose that 25.0mL of a solution of Ag+ ions of unknown concentration is
titrated with 0.015M KI(aq) at 25℃. A silver electrode is immersed in this
solution, and its potential is measured relative to a standard hydrogen
electrode. A total of 16.7mL of KI(aq) was required to reach the
stoichiometric point, when the potential was 0.325V.(The standard reduction
potential of Ag+ is 0.80V)
(a)What is the molar concentration of Ag+ in the solution?
(b)Determined Ksp for AgI by using the electrochemical data.
(c)Sketch the potentiometric titration curve(emf vs. titrant(mL of KI(aq)))
(9%)
-
12.The reduction of ClO4 can be conducted in either basic or acidic
solutions. The two half-reactions are
- + - - o
(1,acidic) ClO4 (aq)+2H (aq)+2e →ClO3 (aq)+H2O(l) E =+1.23V
- - - - o
(2,basic) ClO4 (aq)+H2O(l)+2e →ClO3 (aq)+2OH (aq) E =+0.36V
(a)Show how these processes are related by deriving an expression that gives
the pH dependence of the emf for each half-reaction.
(b)What is the potential of each reaction in neutral solution?(6%)
13.(a)Derive the integrated rate law for third-order reaction with the rate law
-d[A]/dt=k[A]^3.
(b)What kind of plot (function of concentration as time t) will be expected
a straight line?(6%)
14.A proposed mechanism for the reaction A + B + E → D + X + Y is
A + B <-> C + D k1,k-1
C + E → X + Y k2
(a)Derive a rate law for the formation of X.(Suppose that k1, k-1, k2 are all
approximately the same magnitude and apply steady-state approximation to C.)
(b)Show that, in the limit of a large excess of E, the rate law obtained in
part(a) is second order. (c)Explain physically why the result obtained in
part(b) is reasonable(9%)
15.The rate law of the reaction 2NO(g)+2H2(g)→N2(g)+2H2(g)
is rate=k[NO]^2[H2], and the mechanism that has been proposed is
Step1 NO + NO <-> N2O2
Step2 N2O2 + H2 → N2O + H2O
Step3 N2O + H2 → N2 + H2O
(a)Which step in the mechanism is likely to be rate determining? Explain
your answer. (b)Sketch a reaction profile for the overall reaction, which
is known to be exothermic. Label the activation energies of each step and
the overall reaction enthalpy.(6%)
16.(a)Sketch the orbital energy-level diagrams for [MnCl6]4- and [Mn(CN)6]4-.
(b)How many unpaired electrons are present in each complex? (c)Which complex
absorbs the longer wavelengths of incident electromagnetic radiation?
Explain your reasoning.(9%)
17.Two chemist prepared a complex and detemined its formula, which they wrote
as [Cr(NH3)Cl3]‧2H2O. However, when they dissovled 2.11g of the compound
in water and added an excess of silver nitrate, 2.87g of AgCl precipitated
and they realized that the formula was incorrect. (a)Write the correct
formula of the compound. (b)Draw its structure, including all possible
isomer, assuming possible coordination geometry are tetrahedral and
octahedral, amd name them(neglect the nomenclature of stereoisomers).
(Atomic weight: Cr 52.00, Cl 35.45, Ag 107.9, N 14.01, O 16.00)(12%)
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