CHEM 1110                                                                                                                                                           Print Name_____________

Dr. Perona                                                                                                                                                             March 10, 2004

                                                                                                EXAM 1

Part 1. MULTIPLE CHOICE. (60 points)  Questions 1-20 are multiple choice, worth 3 points each.  Mark the letter corresponding to the one correct answer on your scantron sheet.

1)  Which has the smallest dipole-dipole forces?

A) CO

B) N₂

C) CH₃F

D) HCl

2)  Which is expected to have the largest dispersion forces?

A) C₈H₁₈

B) CO₂

C) C₂H₆

D) N₂

3)  Which of the following compounds exhibits hydrogen bonding?

A) CH₃Cl

B) H₃C-O-CH₃

C) HI

D) NH₃

4)  Which of the following compounds has the highest boiling point?

A) CH₃CH₂CH₂CH₃

B) HOCH₂CH₂OH

C) CH₃CH₂OH

D) H₃C-O-CH₃

5)  CFC-11 (trichlorofluoromethane, CCl₃F) has been used for many years as the working fluid in refrigerators. Given its heat of vaporization is 26.88 kJ/mol and its entropy of vaporization is 90.51 J/(mol \'97 K), what is the boiling point of CFC-11?

A) 0.297eC

B) 23.8eC

C) 2.44eC

D) -272.9eC

6)  For which of the following processes is the sign of DS negative?

A) boiling of water

B) sublimation of I₂

C) melting of ice cream

D) formation of snow from water vapor in clouds

7)  The normal boiling point occurs when the

A) vapor pressure of the liquid equals the external pressure.

B) intermolecular forces within the liquid phase are broken.

C) temperature of the pure liquid equals the external temperature.

D) vapor pressure of a pure liquid equals an external pressure of one atmosphere.

8)  How many atoms are in one body-centered cubic unit cell of a metal?

A) 1

B) 2

C) 3

D) 4

A certain mineral crystallizes in the cubic unit cell shown below in which unshaded spheres represent cations and shaded spheres represent anions.

9)  How many cations and how many anions are in the unit cell?

A) 4 cations and 4 anions

B) 8 cations and 4 anions

C) 4 cations and 14 anions

D) 4 cations and 8 anions

10)  Which drawing best accounts for the polarity of methanol, CH₃OH, and the bond polarities that make a major contribution to the overall molecular polarity?

A) drawing (1)

B) drawing (2)

C) drawing (3)

D) drawing (4)

11)  The critical temperature of a substance is the

A) temperature above which the compound decomposes.

B) temperature at which all three phases can exist in equilibrium.

C) temperature at which sublimation occurs.

D) highest temperature at which the liquid phase can exist in equilibrium with the gas phase.

12)  Which of the following solutions will have the lowest freezing point?

A) 0.015 m MgCl₂

B) 0.0100 m Li₂SO₄

C) 0.035 m CH₃CH₂CH₂OH

D) 0.0100 m NaCl

13)  What is the molality of a glucose solution prepared by dissolving .0 g of glucose, (C₆H₁₂O₆,  molar mass = 180  g/mol) in 125.9 g of water?

A)  þ 10^- m

B) 0. m

C) m

D) m

The phase diagram of a substance is shown below.

14)  The approximate normal boiling point of this substance is

A) 180 K.

B) 300 K.

C) 430 K.

D) 190 K.

15)  What is the physical phase of the substance at T = 225 K and P = 1.1 atm?

A) liquid

B) supercritical fluid

C) solid

D) gas

16)  the approximate normal melting point of this substance is

A) 180K

B) 190 K

C) 300 K

D) 430 K

17)  Arrange the following compounds in order of their expected increasing solubility in water: KCl, CH₃CH₂-O-CH₂CH₃, CH₃CH₂CH₂CH₂-OH, CH₃CH₂CH₂CH₂CH_3.

A) CH₃CH₂CH₂CH₂CH₃ < CH₃CH₂-O-CH₂CH₃ < KCl < CH₃CH₂CH₂CH₂-OH

B) CH₃CH₂CH₂CH₂CH₃ < CH₃CH₂-O-CH₂CH₃ < CH₃CH₂CH₂CH₂-OH < KCl

C) CH₃CH₂CH₂CH₂CH₃ < KCl < CH₃CH₂-O-CH₂CH₃ < CH₃CH₂CH₂CH₂-OH

D) KCl < CH₃CH₂-O-CH₂CH₃ < CH₃CH₂CH₂CH₂-OH < CH₃CH₂CH₂CH₂CH₃

18)  In general, as the temperature increases, the solubility of gases in water ________ and the solubility of most solids in water ________.

A) decreases, increases

B) decreases, decreases

C) increases, increases

D) increases, decreases

19)  In which case should CO₂(g) be more soluble in water?

A) The total pressure is 3 atm and the partial pressure of CO₂ is 2 atm.

B) The total pressure is 5 atm and the partial pressure of CO₂ is 1 atm.

C) The total pressure is 1 atm and the partial pressure of CO₂ is 0.03 atm.

D) The total pressure is 1 atm and the partial pressure of CO₂ is 0.5 atm.

20)  Drawing (1) shows the equilibrium vapor pressure of a pure liquid. Which drawing (2)-(5) represents the equilibrium vapor pressure when a nonvolatile solute is dissolved in the liquid?

A) drawing (2)

B) drawing (3)

C) drawing (4)

D) drawing (5)

Part 2. You must show all of your work in the following problems to obtain full credit .

21)  (10) The density at 20^oC of a 3.299 M solution of ethylene glycol in water is 1.0241 g/mL.  What is the concentration of this solution in molality?  The molar mass of ethylene glycol, C₂H₄(OH)₂ is 67.07 g/mol.

22)  (10) What is the freezing point of a solution prepared by dissolving 15.00 g of urea CH₄N₂O in 200.0g of water.  The molar mass of urea is 60.00 g/mol.  For water, K_f = 1.86 (^oC^.kg)/mol, and it normal freezing point is 0.00 ^oC.

23)  (10) The vapor pressure of mercury is 39.3 mm Hg at 500K, and its normal boiling point is 630 K.  What is the enthalpy of vaporization, ÆH_vap,  of mercury in kJ/mol?

24)  (10) A solution containing  62.4 g of the compound insulin  in 1.000 L of aqueous solution has an osmotic pressure of 0.305 atm at 298 K.

                a)  What is the molarity of the solution?

                b)  What is the molar mass of insulin?