课程名称︰普通化学乙下 课程性质︰必带 课程教师︰牟中原教授 开课学院：理学院 开课系所︰化学系 考试日期（年月日）︰99/04/13 考试时限（分钟）：10:20~12:15 是否需发放奖励金：yes （如未明确表示，则不予发放） 试题 : 1. Please explain the following terms: (24%) (a) Describe Downs cell for producing metallic sodium (Materials used and draw the cell) (b) Cathode protection of underground pipe (c) Describe aluminum production from electrolysis process (Materials used and draw the cell) (d) Lotus effect: why water does not stick to lotus leave 2. Derive the formula for collision frequency on a surface of area A, ZA=(1/4)(N/V)A(8RT/(pi*M))^-1/2=A(N/V)(RT/(2piM))^-1/2 Where M is molecular weight and T is temperature of the gas. In an effusion experiment, the pressure of one mole of water vapor is 1 torr and T=300K. How long does it take to leak half of the gas if the pin-hole area is 0.00001 cm^2? (14%) 3. Answer the following questions avout Van der Vaals(VDW) equation (a) Please write down the Van der Vaals quation of state for non-ideal gas (b) Explain the physical meaning of all the parameters. (c) Explain the reasoning of writing down this equation. (d) Rank in decreasing order the value of "a" constant in VDW eq for Carbon dioxide, nitrogen, water, xenon, neon. (18%) 4. A group 3A metal has a density of 2.70g/cm^3 and cubic unit cell with an edge length of 404 pm. Reaction of a 1.07 cm^3 chunk of the metal with an excess of hydrochloric acid gives a colorness gas that occupies 4.00L at 296K and a pressure of 740 mmHg. (a) Identify the metal. (b) Is the unit cell primitive, body-centered, or face-centered? (c) What is the atomic radius of the metal atom? (14%) 5. Please fraw the phase diagram of water to show: a. critical point b. triple point c. explain the slope of the soild-liquid coexistence line d.draw the temperature vs time curve at a constant pressure of 1 atm from 240K to 400K as one heats a sample of ice until to vapor. e. draw the corrsponding T vs t curve but at a pressure above critical pressure. (14%) 6. A Helium/hot air balloon consists of a closed center Helium balloon and a expandable hot air balloon surrounding He balloon in the outer shell(shown as below). The He balloon was filled with 36kg He(g). The total weight load of the balloon is 600kg (including the gases and balloon). The density of air is 1.29kg/m^3 (a) Without hot air does the balloon take off at 1atm 298K? (b) If not, how many amounts of fuel(propane) are needed to enable the balloon take off? Assume all gases in the combustion reaction are ideal gases and the temperature of all gases is at 373K in the hot air balloon. (16%) --

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