All Notes, Books, Etc., Must Be Placed out of Sight. Please Read Each of the Problems Carefully s2

Chemistry 152 Exam I Spring, 1997

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 11 problems on 5 pages. 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!

(liter atm) Joule 760 mm Hg = 760 Torr = 1 Atm R = 0.0821 = 8.31 2.54 cm = 1 inch 12 inch =1 ft (mole K) (mole K) 5280 ft = 1 mile 1 picture = 1 kiloword

Solvent Boiling Point KBP Melting Point KFP P(20 C) Pure Hvap (C) (C) Vapor Pressure

Water 100 0.512 0 1.86 17.5 43.9 kjoule/mole Chemistry 152 Exam I Page 1 Name

1.(16) From the data listed in the following table, determine the normal boiling point of liquid nitric acid. Show all of your work clearly for full credit.

Temperature (C) Vapor Pressure (mm Hg) 0 14.4 10 26.6 20 47.9 30 81.3 40 133 50 208 80 670

2.(10) Calculate the molarity and mole fraction of acetone in a 1.00 m solution of acetone (C3H6O MW = 58) in ethanol (C2H6O MW = 46). The density of acetone is 0.788 g/cm3 and the density of the ethanol is 0.789 g/cm3. Assume that the volumes of acetone and ethanol are additive. Show all work for full credit. Chemistry 152 Exam I Page 2 Name

3.(10) The newly discovered element, Braunium, has some very strange physical properties. Consider the following data: Two forms of the solid, BS1 and BS2 exist

BS2 melts at 160C BS1 is more dense than BS2 There are two triple points: 75C, 0.5 atm 150C, 0.75 atm The liquid boils at 200C The critical point is 225C, 1,5 atm

Draw the phase diagram for Braunium.

4.(15) In each of the following groups of substances, pick the one that has the given property and supply a BRIEF statement as to why you chose that answer. a. Highest boiling point: HCl Ar F2

b. Lowest vapor pressure at 25C: Cl2 Br2 I2

c. Lowest boiling point: CH4 CH3CH3 CH3CH2CH3

d. Highest boiling point: HF HCl HBr

e. Greatest heat of vaporization: H2O H2S H2Se Chemistry 152 Exam I Page 3 Name

5.(10) A solution contains 3.75 g of a non-volatile pure hydrocarbon in 95 g of acetone. The boiling points of pure acetone and the solution are 55.95C and 56.50C respectively. The molal boiling point constant of acetone is 1.71 C/m. What is the molecular weight of the hydrocarbon? Show all work clearly for full credit.

6.(18) a. Calculate the freezing point depression and the osmotic pressure at 25C of an aqueous solution containing 1.0 g/L of a protein (MW = 9.0 x 104 grams/mole) if the density of the solution is 1.0 g/cm3. Show all work clearly for full credit.

b. Considering your answers in part (a), which colligative property, freezing point depression or osmotic pressure would be better used to determine the molecular mass of a large molecule? Try to explain your choice.

7.(5) Briefly describe for me dispersion (London) forces. In particular, make sure you compare and contrast the London forces to dipole-dipole forces.

8.(5) You and a friend are each drinking Coca Cola from separate 2 L bottles. Both cokes are Chemistry 152 Exam I Page 4 Name

equally carbonated. You are able to drink 1 L of coke, but your friend can only drink about  liter. You each close the bottles and place them in the refrigerator. The next day when you each go to get the cokes, whose will be more carbonated and why?

9.(5) We always purchase hydrochloric acid as 12 M HCl. Dave (the lab guy) tells me we need 6.5 liters of a 3.5 M HCl solution for the kiddie Chem lab next week. How much of the 12 M HCl should I make sure we have in the stock room. Show your work.

10.(5) Consider the diagram at the right which is a picture of this system at the instant we mixed the two solutions. The semipermeable membrane is permeable to water only. What would happen to the level of liquid in the left-hand side of the apparatus once equilibrium is established? Explain your response briefly.

11.(1) What is the name of the scientist for which London forces are named? ______Chemistry 152 Exam I Page 5 Name