CHEM 1120-002                    QUIZ 2                      FORM A                 February 10, 2006

 

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___ 19.  Which of the following solutions would not be
expected to exist?

a)

NaCl in water

b)

Pentane, C5H12, in CCl4

c)

Methyl alcohol, CH3OH, in water

d)

Vegetable oil in mineral oil

e)

NaCl in CCl4

 

 

___ 20.  Which one of the following statements is false?

a)

The solvation process usually absorbs heat.

b)

Nonpolar solids do not dissolve appreciably in polar solvents.

c)

The solubility of a gas that does not react with the solvent

decreases as temperature increases.

d)

The separation of solute particles from a crystal requires

energy.

e)

The effects of lattice energies and hydration energies

Oppose each other in the dissolution of solids in liquids.

 

 

___ 21.  The dissolution process is exothermic if the amount of energy released in bringing about  a  interactions exceeds the sum of the amounts of energy absorbed in overcoming  b  and  c  interactions.

     a  

  b  

  c  

 

a)

solvent-solvent     solute-solute        solvent-solute

b)

solvent-solute      solute-solute        crystal lattice

c)

solute-solute       crystal lattice      solvent-solvent

d)

solvent-solute      solute-solute        solvent-solvent

e)

solute-solute       solvent-solvent      solvent-solute

 

 

___ 22.  What is the molality of an aqueous solution that is 10.0% ethanol, C2H5OH, by mass?

a)

1.77 m

b)

2.17 m

c)

2.42 m

d)

2.66 m

e)

1.38 m

 

___ 23. . What is the mass % solute of a 2.00 molal H2SO4 solution in water?

a)

9.8 %

b)

19.6 %

c)

2.0 %

d)

16.4 %

e)

1.1 %

 

___ 24. The solubility of nitrogen (N2) in blood at 0.78 atm  and 37oC (physiological conditions on land)  is 1.65 mg/L.  What would be the concentration of N2 in the blood at 2.50 atm (deep-sea diving conditions) at the same temperature?

a)

11.8 mg/L

b)

5.29 mg/L

c)

4.12 mg/L

d)

0.515 mg/L

e)

Not enough information

To determine

 

___ 25.  For salts which are more soluble in cold water than in hot water…

a)

the lattice energy is greater than the hydration energy

b)

the heat of solution is positive

c)

the dissolution process is endothermic

d)

the hydration process is endothermic

e)

the hydration energy  is greater than the lattice energy

 

___ 26.  A solution contains 10.0 g pentane, C5H12, 10.0 g hexane, C6H14 and 10.0 g benzene, C6H6. What is the mole fraction of hexane?

a)

0.116

b)

0.333

c)

0.362

d)

0.335

e)

0.303

 

 

___ 27.  Calculate the boiling point of a solution prepared by dissolving 70.0 g of naphthalene, C10H8 (a nonvolatile nonelectrolyte), in 220.0 g of benzene, C6H6. The Kb for benzene = 2.53oC/m. The boiling point of pure benzene is 80.1oC.

a)

73.8oC

b)

83.2oC

c)

86.4oC

d)

106.3oC

e)

87.8oC

 

___ 28.  What is the vapor pressure of a aqueous solution containing 10 %(by weight) ethylene glycol (62 g/mol) at 25 oC. PH2O= 24.3 torr at 25 oC.

a)

21.9 torr

b)

23.5 torr

c)

18.9 torr

d)

0.761 torr

e)

25.1 torr

 

 

___ 29.  A colloid can be easily distinguished from a “true solution”  because a colloidal dispersion….

a)

tends to exhibit a lower boiling point than the pure solvent

b)

will scatter light, producing a non-transparent medium

c)

will be repelled by an electric field

d)

will form even if DHsoln is endothermic

e)

is transparent

 

___ 30.  Which of the following statements regarding a 1 M sucrose solution is not correct?

a)

The freezing point is less than that of a 1 M NaCl solution.

b)

The freezing point is less than 0.0oC.

c)

The boiling point is less than that of a 1 M NaCl solution.

d)

The vapor pressure at 100oC is less than 760 torr.

e)

The boiling point is greater than 100oC.

 

 

___ 31.  Iodine (I2) is more soluble in carbon tetrachloride (CCl4) than water because…

a)

iodine and CCl4 are both nonpolar while water is polar

b)

iodine and water exhibit similar intermolecular attractions

c)

both iodine and CCl4 contain halogens

d)

iodine and CCl4 are  both polar while water is nonpolar

e)

iodine and CCl4 possess similar molecular weights

 

 

___ 32.  What is the molecular weight of a polymer if 1.55 g of it dissolved in 100 mL of water generates osmotic pressure equal to 15.2 torr at 25oC?

a)

24.3 g/mol

b)

624 g/mol

c)

19.0 g/mol

d)

19,000 g/mol

e)

24,100 g/mol

 

 

___ 33.  The freezing point of an aqueous solution containing 15 g of a nonelectrolyte in 150 mL water is -5.4oC. What is the molecular weight of the compound ?
K
f = 1.86oC/m for water.

a)

2.78 g/mol

b)

34.4 g/mol

c)

41.2 g/mol

d)

53.8 g/mol

e)

121 g/mol

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CHEM 1120-002

Quiz 2 Keys

(See Form A to correlate with questions on other forms.)

 

Test Form

Question #

A

B

19

e

e

20

a

a

21

d

b

22

c

c

23

d

d

24

b

e

25

e

a

26

e

a

27

c

c

28

b

d

29

b

b

30

a

c

31

a

e

32

d

a

33

b

b