课程名称︰普通化学丙 课程性质︰药学 医技 护理 物治 职治 公卫 必带 课程教师︰刘铭璋 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰20131127 考试时限（分钟）：120 是否需发放奖励金：是 （如未明确表示，则不予发放） 试题 : 本次测验范围为Chemistry: An atoms first approach 4.7~4.12, chap 5 and chap 8. 1.Consider the following reaction: A + B → 2AB ΔE=-285 kJ 2 2 The bond energy for A is one-half the amount of the AB bond energy. The bond 2 energy of B = 432 kJ/mol. What is the bond energy of A ? (4%) 2 2 2. (1)Write Lewis structures that obey the octet rule (duet rule for H) for each following molecules. (2)Also predict the molecular structures and bond angles. (3)Give the expected hybridization of the central atom. (4)Which of the molecule(s) or ions are polar? _ _ (a)IF (b)NCl (c)PCl (d)I (e)SeO (26%) 4 3 5 3 3 3.Nitrus oxide (N2O) has three possible Lewis structures: (图片：http://i.imgur.com/eRoYyY0.png) Give the following bond lengths, N-N 167 pm, N=N 120 pm, N≡N 110 pm, N=O 115 pm, N-O 147 pm. Rationalize the observations that the N-N bond length in N2O is 112 pm and that the N-O bond length is 119 pm. Assign formal charges to the resonance structures for N2P. Can you eliminate any of the resonance structures on the basis of formal charges? Is this consistent with observation? (6%) 4.Describe the bonding in the ethylene molecule (C2H4), using the localized electron model. Why must all six atoms in C2H4 lie in the same plane? (5%) 5.Sketch the molecular orbital and label its type (σorπ, bonding or antibonding) that would be formed when the following atomic orbitals overlap. Explain your labels. (9%) (图：http://i.imgur.com/wR5dcbw.png) 6.Using the molecular orbital model, (1)write electron configurations for the following diatomic species and (2)calculate the bond orders. (3)Predict their magnetism. Place the species in order of increasing bond length and bond energy. (8%) a. CN+ b. CN 7.Calcium has a cubic closest packed structure as a solid. Assuming that calcium has an atomic radius of 197 pm, calculate the density of solid calcium. Ca:40.08 amu (6%) 8.In each of the following groups of substances, pick the one that has the given property. Justify you answer. (12%) a.highest freezing point: H2O, NaCl or HF b.highest boiling point: Cl2, Br2 or I2 c.highest boiling point: CH3OCH3, CH3CH2OH or CH3CH2CH3 d.smallest enthalpy of fusion: benzene, Cu, or CaO 9.(1)What is n-type semiconductor? (2)Give an example. (3)Draw the energy-level diagram for an n-type semiconductor and explain the doping effect on its conductivity. (4)Explain how a p-n juction makes an excellent rectifier (converting the alternating current to direct current). (8%) 10.What type of solid will each of the following substances form? a.CO2 b.SiO2 c.Cu d.CaCO3 e.Ar (5%) 11.Use the localized electron model to describe the bonding in H2O. Draw a rough structure of ice, and explain why ice is less dense than water. Why there is maximum density of water at 4°C. (6%) 12.(a)Draw the structures of diamond and graphite. (b)Explain why diamond is harder than graphite. (c)Why is a graphite an electrical conductor but diamond is not? (6%) 13.Consider the phase diagram given below. What phases are present at points A through F? Identify the triple point, normal boiling point, and critical point. Which phase is denser, solid or liquid? (5%) (图：http://i.imgur.com/LqlUygz.png) --

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