课程名称：普通化学乙上 课程性质︰必修 课程教师︰林英智 开课学院：生农学院 开课系所︰森林环资系 考试日期（年月日）︰2014/01/08 考试时限（分钟）：110分钟 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : Avogadro's number NA=6.02x10^23 Gas constant R=0.0821 Latm/molK = 8.31 J/molK 1. Chromium crystallizes with a body-centered cubic unit cell. The radius of a chromium atom is 125 pm. Calculate the density of solid crystalline chromium in g/cm3 . Atomic weight Cr 52.0. 2. Methanol has a normal boiling point of 64.6°C and a heat of vaporization of vaporation (△Hvap) of 35.2 KJ/mol. What is the vapor pressure of methanol at 45°C. 3. Draw the shape of all eight molecular orbitals from linear combination of one 2s and three 2p atmoic orbitals for homodiatomic molecule. 4. Draw two energy level diagrams of the molecular orbital of 2s and 2p for B2 and O2. Explain why both of them are paramagnetic. Find the bond order of B2, B2+ and O2,O2+. 5. Using VSEPR to predict the structure of the following molecules: SF4, BrF3, BrF5, XeF2, XeF4. 6. Three 1.0 flasks, at 308K, are connected to each other with stopcocks. One of the flasks contains 1.0 atm of N2, the second 0.10g of H2O; the third 0.40g of ethanol C2H5OH when the stopcocks are closed. The vapor pressure of H2O is 42 mm-Hg and that of ethanol is 102 mm-Hg at 308K. What is the pressure when the stopcocks are opened and the contents mix greely? 7. Draw the structures of two compounds that have the composition CH3NO2 and have all three H atoms bonded to the C. Predict which compound has the larger ONO bond angle. 8. (a) Make sketch of three resonances forms for methylazide(CH3N3). (b) Use VSEPR to predict the geometry and formal charge of three nitrogen atoms. (c) Compare the bond angles of interior nitrogen toms and two nitrogen-nitrogen bond lengths. 9. Tetrahedral hole is formed when four spheres of radius r are in contact and plsced at alternate corners of a cube. The hole is inside the middle of the cube. Find the length of the body diagonal of this cube and the radius of the tetrahedral hole. 10. Butane(C4H10) has a heat of vaporization of 22.44 KJ/mol and a normal boiling point of -0.4°C. A 150 mL sealed flask contains 0.40g of butane at -20°C. How much butane is present as a liquid? If the butane is warmed to 20°C, how much is present as a liquid and find the final pressure? --

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