Chemistry 1212 Exam I Page 1 Name
Chemistry 1212
Exam I
Summer, 2003
Name______
All notes, books, etc., must be placed out of sight. Please read each of the problems carefully. If something is not clear, please ask.
The exam consists of 8 problems on 4 pages with a Take-Home extra credit opportunity on the fourth page. Make sure your exam is complete. The exam is worth 100 points with each of the problems labeled as to its point value.
Answers should be placed in the space provided and written legibly. If I cannot read it -- it is wrong. You MUST show your work clearly for each problem in order to receive full credit. Please include an explanation whenever asked to or whenever necessary to make your answer clear. If I cannot understand it -- it is wrong. Please put your name on every page of the exam.
There are scratch papers and periodic tables available for your use. If you require more data, please ask.
As usual, no cheating is allowed. Good Luck!
DATA
760 mm Hg = 760 Torr = 1 Atm
1 picture = 1 kiloword
Substance / Density / Freezing Pt / kfp / Boiling Pt / kbp / HvapH2O / 1.0 g/ml / 0.0 C / 1.86 / 100.0 C / 0.512 / 40.79 kJ/mole
1.(15) The vapor pressure of SiCl4 (MW = 170.1) is 100 mm Hg at 5.4ºC, and the normal boiling point is 56.8ºC. What is Hvap for SiCl4? Show all work clearly for full credit.
2.(10) What is the vapor pressure of SiCl4 at 30.0ºC? Show all work clearly for full credit.
3.(15) Braunine has a triple point of –7.3ºC and 228 mm Hg. Its critical point is 115 ºC and 1.8 atm. The density of the liquid is 3.1 g/cm3 and the density of the solid is 3.4 g/cm3. The liquid boils at 60ºC and 0.70 atm. Sketch the phase diagram for this substance.
a. Label the appropriate regions as Solid, Liquid, and Vapor.
b. Assign each axes a label and unit.
c. Estimate the normal boiling point of braunine.
d. Which phase or phases are present under the conditions of T = –10ºC and P = 10 mm Hg?
4.(15) Nalorphine, C19H21NO3 (MW = 311), a relative of morphine, is used to combat withdrawal symptoms in narcotics users. How many grams of a 1.3 x 10-3 m aqueous solution of nalorphine are needed to obtain a dose of 1.5 mg? Show all work clearly for full credit.
5.(10) How many grams of water should you add to 32.5 g of sucrose, C12H22O11 (MW = 342), to get a 0.850 m solution? Show all work for full credit.
6.(10) What is the vapor pressure of a solution of 10.0 g of LiCl (MW = 42.4) in 150.0 g of H2O (MW = 18) at 45ºC, assuming complete dissociation? The vapor pressure of pure water at 45.0ºC is 71.93 mm Hg. Show all work clearly for full credit.
7.(10) Fluorine is more electronegative than chlorine, yet fluoromethane, CH3F, has a smaller dipole moment than chloromethane, CH3Cl. Explain briefly but clearly.
8.(15) An aqueous solution containing 100.0 g of NaCl (MW = 58.5) and 100.0 g of CaCl2 (MW = 111.1) has a volume of 1.00 L and a density of 1.15 g/ml. The vapor pressure of pure water at 25ºC is 23.8 mm Hg and you can assume complete dissociation for both solutes. Determine either the boiling point OR the vapor pressure of the solution at 25ºC. Your choice. Show all work clearly for full credit.