课程名称︰物理化学二 课程性质︰必修 课程教师︰陈立仁 开课学院：工学院 开课系所︰化工系 考试日期（年月日）︰2012/3/19 考试时限（分钟）：110 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : Problem 1. Determine E°for the reaction Cr2+ + 2e- → Cr Available data: Cr3+ + 3e- → Cr E°=-0.774V Cr3+ + e- → Cr2+ E°=-0.407V problem 2. The data in the following table have been obtained for the potential of the cell Pt(s)|H2(g,1bar)|HCl(aq,m)|AgCl(s)|Ag(s) as a function of m at 25℃. ┌─────┬─────┬─────┬─────┐ │m(mol/kg) │ E(V) │m(mol/kg) │ E(V) │ ├─────┼─────┼─────┼─────┤ │0.00100 │0.59715 │0.0200 │0.43024 │ ├─────┼─────┼─────┼─────┤ │0.00200 │0.54425 │0.0500 │0.38588 │ ├─────┼─────┼─────┼─────┤ │0.00500 │0.49846 │0.100 │0.35241 │ ├─────┼─────┼─────┼─────┤ │0.0100 │0.46417 │0.200 │0.31874 │ └─────┴─────┴─────┴─────┘ a)Determine E°of the cell using a graphical method. b)Calculate γ±for GCl at m=0.00100, 0.0100, 0.100 mol/kg. Problem 3. The equilibrium constant for the hydrolysis of dimethylamine (CH3)2NH(aq) + H2O(aq) → CH3NH3+(aq) + OH-(aq) is 5.12*10^(-4). Calculate the extent of hydrolysis for (a) a 0.125m solution of (CH3)2NH in water and (b) a solution that is also 0.045m in NaNO3. Note that the extent of hydrolysis means the percentage of dimethylamine is hydrolyzed. Problem 4. The proton possesses abnormal mobility in water, but does it behave normally in liquid ammonia? To investigate this question, a moving-boundary technique was used to determine the transport number of NH4+ in liquid ammonia (the analogue of H3O+ in liquid water) at -40℃. A steady current of 5.000mA was passed for 2500s, during which time the boundary formed between mercury(II) iodide and ammonium iodide solutions in ammonia moved 286.9mm in a 0.01365 mol/kg solution and 92.03mm in a 0.04255 mol/kg solution. Calculate the transport number of NH4+ at these concentrations, and comment on the mobility of the proton in liquid ammonia. The bore(diameter) of the tube is 4.146mm and the density of liquid ammonia is 0.682g/cm^3. Problem 5. Two equal volumes of 0.300M NaCl(aq) are seperated by a membrane. A macromolecule of molar mass 33kg/mol, which cannot pass through the membrane, is added as its sodium salt Na10P in a concentration of 50.0g/L to the left- hand compartment. The membrane is permeable to Na+ and Cl-. (a) What are the equilibrium concentrations of Na+ and Cl- in each compartment? (b) What is the potential difference across the membrane arising from the Na+ ion concentration difference at 25℃? (c) Calculate the osmotic pressure across the membrane. Problem 6. The standard cell potential of Pt(s)|H2(g)|HBr(aq)|AgBr(s)|Ag(s) was measured over a range of temperatures and the data were fitted to the following polynomial: E°/V=0.07131-4.99*10^(-4)(T-298)-3.45*10^(-6)(T-298)^2 T=[K] Evaluate the standard reaction Gibbs energy, enthalpy and entropy at 298K. --

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