课程名称︰物理化学上 课程性质︰必修 课程教师︰陈振中 开课学院： 开课系所︰农化系 考试日期（年月日）︰ 2011.01.13 考试时限（分钟）： 110 mins 是否需发放奖励金： 是 （如未明确表示，则不予发放） 试题 : Section A (80%) 1. (10%)Liquid mercury has a density of 13.7 g/cm3, and solid mercury has a density of 14.2 g/cm3, both being measured at the melting point, -38.87 ℃, at 1 bar pressure. The heat of fusion is 9.75 J/g. Calculate the melting points of mercury under a pressure of (a)10 bar and (b)2540bar. 2. (12%)Ethanol and methanol form very nearly ideal solutions. At 20℃, the vapor pressure of ethanol is 5.93 kPa, and that of methanol is 11.83 kPa. (a)Calculate the mole fractions of ethanol and methanol in a solution obtained by mixing 120 g of each. (b) Calculate the total vapor pressure of the solution. (c) Calculate the mole fraction of ethanol in the vapor. 3. (12%)The solubility of Ag2CrO4 in water is 8.00*10^-5 mol/kg at 25℃, and its solubility in 0.04 mol/kg NaNO3 is 8.84*10^-5 mol/kg. What is the mean ionic activity coefficient of Ag2CrO4 in 0.04 mol/kg NaNO3? 4. (10%)Calculate ΔmixG and ΔmixS for the formation of a quantity of air containing 2 mol of gas by mixing nitrogen and oxygen at 350 K. Air may be taken to be 80% nitrogen and 20% oxygen. 5. (10%)Calculate the extent of reaction α of 1 mol o H2O(g) to form H2(g) and O2(g) at 2000 K and 1 bar. (Since the extent of reaction is small, the calculation may be simplified by assuming that PH2O = 1bar.) 1 H O (g) → H (g) + — O (g) 2 ← 2 2 2 6. (16%)The NBS tables contain the following data at 298 K: ΔrH。/ kJ/mol ΔrG。/ kJ/mol CuSO4(s) -771.36 -661.8 CuSO4．H2O(s) -1085.83 -918.11 CuSO4．3H2O(s) -1684.31 -1399.96 H2O(g) -241.818 -228.572 (a)What is the equilibrium constant over a mixture of CuSO4(s) and CuSO4．H2O(s) at 298 K? (b)What is the equilibrium constant over a mixture of CuSO4(s) and CuSO4．3H2O(s) at 298 K? (c)What is the answer to (a) if the temperature is 596 K and ΔCp。 is assumed to be zero? 7. (10%)Calculate the molar Gibbs energy G of fusion when supercooled water at -10℃ freezes at constant T and P. The enthalpy of fusion of ice is 6000 J/mol at 0℃. The heat capacities of water and ice in the vicinity of freezing point are 75.3 and 38 J/ K mol, respectively. Section B (20%) 1. (10%)Consider a mixture of two liquids, A and B. The following diagram shows the experimental partial pressure of A and B, denoted as PA and PB, respectively. 图略 (a) Compare the intermolecular interaction of A-B with that of A-A or B-B. Explain why. (b) On the basis of the figure, estimate the activity coefficients of B at xB = 0.5. Provide your answer to the nearest digit. For example, the PA value at xB = 0 can be estimated as 82 Pa and the PB value at xB = 1 be 36 Pa.[Hints: The Henry's constant of B is 78 Pa] 2. (10%)The following diagram shows a typical PV diagram taken from the textbook (Fig.3.14): 图略 The curve from A to B corresponds to isothermal expansion at temperature T1 and that from C to D corresponds to isothermal compression at temperature T2.The two curves from B to C and from D to A are adiabatic processes. (a) Is it possible to have two adiabatic processes cross at a particular state as shown below ? Justify your statement.[Hint:Design a cyclic process and consider the change of a state function]图略 (b) Consider an adiabatic process which starts and ends at two different temperatures. Can the process start or end at 0 K ? ________ CdT dS = —— T ΔG。 = ΔH。- TΔS。 _ dP ΔH —— = ——_ dT TΔV ν± a = (γ m ) Aν+Bν- ±± log γ = Az z √I (A = 0.509 kg^1/2 mol^1/2 for aqueous solution at 298.15 K ± + - --

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