The following data present the temperatures at which certain vapor pressures are achieved for dichloromethane (CH2Cl2) and methyl iodide (CH3I):

(a)Which of the two substances is expected to have the greater dipole-dipole forces? Which is expected to have the greater dispersion forces? Based on your answers, explain why it is difficult to predict which compound would be more volatile.
(b)Which compound would you expect to have the higher boiling point?
Check your answer in a reference book such as the CRC Handbook of Chemistry and Physics.
(c) The order of volatility of these two substances changes as the temperature is increased. What quantity must be different for the two substances in order for this phenomenon to occur?
(d) Substantiate your answer for part
(c) by drawing an appropriate graph.

Transcribed Image Text:

Vapor Pressure (torr) Tfor CH2Cl2 (°C): -43.3-22.3-6.3 T for CH3l (C):45.8-24.2 7.0 10.0 40.0 100.0 400.0 24.1 25.3