课程名称︰普通化学乙下 课程性质︰必修 课程教师︰林金全 开课学院：工学院 开课系所︰材料系 考试日期（年月日）︰2008/6/17 考试时限（分钟）：160分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 1.The gas-phase reaction between Br2 and H2 to form HBr is assumed to proceed by the following mechanism:(12%) k1 Br → 2Br k-1 k2 Br + H2 → HBr + H k-2 k3 H + Br2 → HBr + Br k4 2Br → Br2 a.Under what conditions does the rate law have the form Rate=k'[Br2]? b.Under what conditions does the rate law have the form Rate=k"[H2][Br2]^1/2? c.Give expression for k' and k" in terms of the rate constants used to define the mechanism. 2.Consider the hypothetical reaction B → E + F which is assumed to occur by the mechanism k1 B + B → B* + B k-1 k2 B* → E + F where B* represents a B molecule with enough energy to surmount the reaction energy barrier.(12%) a.Derive the rate la for production of E using the stead-state approximation. b.Assume that this reaction is known to be first order. Under what conditions does your derived rate law (form part a) agree with this observation? c.Explain how a chemical reaction can be first order, since even in a simples case (B → E + F) molecules must collide to build up enough energy to get over the energy barrier. Why aren't all reaction at least second order? In other words, explain the physical signficance of the result form prat b. 3.A certain reaction has the followin general form: aA → bB At a particular temperature and [A]0=2.80x10^-2 M,concentration versus time data were collected for this reaction, and a plot of ln[A] versus time resulted in a straight line with a slope value of -2.97x10^-2 min^-1. a.Determine the rate law, the integrated rate law, and the value of the rate constant for this reaction.(4%) b.Calculate the half-life for this reaction.(4%) c.How much time is required for the concentration of A to decrease to 2.50x10^-3 M?(6%) 4.In each of the following groups of substances, pick the one that has the given property.Justify your answer.(14%) a.highest boiling point:HCl,Ar, or F2 b.highest freezing point:H2O,NaCl, or HF c.lowest vapor pressure at 25℃:Cl2,Br2 or I2 d.lowest freezing point:N2, CO, or CO2 e.greatest viscosity:H2S,HF, or H2O2 f.greatest heat of vaporization:CH3OCH3, CH3CH2OH, or CH3CH2CH3 g.smallest enthalpy of fusion:I2, CsBr, or CaO 5.Use the accompanying diagram for sulfur to answer th following quiestion. (The phase diagraom is not to scale.) (12%) ┌───────┬────────────┬┐ │ ／153℃,1420atm 　　　　　／ │ │Rhombic ／│ 　Liquid 　　　／ │ │　　　　　/ │　　　　　　　　　　／　　 │ │ 95.39℃/ │115.21℃ ／ │ │--------+----+-----------------／---------│1atm │ /Mono/ 　／444.6℃ 　 │ │ /clin/ ─╯ │ │ / ic /───────╯ │ │ / / 115.18℃,3.2x10^-5atm　　　　　│ │ ／──╯　　　 　Gas 　　│ │─　95.31℃,5.1x10^-6atm 　　　　　│标示之温度及压力皆为交点 └─────────────────────┘ a.How many triple points are in phase diagram? b.What phases are in equilibrium at each of triple points? c.What phase is stable at room temperature and 1.0atm pressure? d.Can monoclinic sulfur exist in equilibrium with wulfur vapor? e.What are the normal melting point and normal boiling point of sulfur? f.which is the denser solid phase, monoclinic or thombic sulfur? 6.What colume of ethylene glycol(C2H6O2), anonelectrolyte, must be added to 15.0 L of water to produce an antifreeze solution with frezing point of -30.0℃? What is the boiling point of this solution? (The density of ethylene is 1.11 g/㎝^3 and the density of water is 1.00 g/㎝^3.)(12%) 7.Asolution saturated with a salt of the type M3X2 has an osmotic pressure of 2.64x10^2 arm ar 25℃. Calculate the Ksp value for the salt, assuming ideal behavior.(12%) 8.The unit cell for xenon fluoride compound is shown in the following diagram. (12%) a.What is the formula of the compound? XeF2(图请参考课本） 　b.The unit cell of XeF2 has a height of 702pm, and the edge of the square base has a length of 432pm. Calculate the density of XeF2. Information: Kf for H2O: 1.86℃kg/mol Hb for H2O: 0.51℃kg/mol --

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