Cliffs AP Chemistry, 3rd Edition

Part B: Question 7 or 8

Directions:No Calculators may be used with Part B. Answer either Question 7 or 8. Only
one of these two questions will be graded. If you start both questions, be sure to cross out the
question you do not want graded. The Section II score weighting for the question you choose
is 15%.

7. If one completely vaporizes a measured amount of a volatile liquid, the molecular weight
   of the liquid can be determined by measuring the volume, temperature, and pressure of the
   resulting gas. When using this procedure, one must use the ideal gas equation and assume
   that the gas behaves ideally. However, if the temperature of the gas is only slightly above
   the boiling point of the liquid, the gas deviates from ideal behavior. Explain the postulates
   of the ideal gas equation and explain why, if measured just above the boiling point, the
   molecular weight deviates from the true value.


8. The boiling points of the following compounds increase in the order in which they are
   listed below:

F 2 < PH 3 < H 2 O

Discuss the theoretical considerations involved, and use them to account for this order.

Part IV: AP Chemistry Practice Test

IF YOU FINISH BEFORE TIME IS CALLED, CHECK YOUR WORK ON THIS

SECTION ONLY. DO NOT WORK ON ANY OTHER SECTION IN THE TEST. STOP