Intermolecular forces l (van der Waals forces) 2.Dipole-Dipole Attraction Attraction- Hδ+ Hδ+ Repulsion----- O11H 6- 6+ H A mix of attractive and repulsive dipole- dipole forces as the molecules tumble
2. Dipole-Dipole Attraction Intermolecular Forces I (van der Waals forces) A mix of attractive and repulsive dipoledipole forces as the molecules tumble
Intermolecular Forces I (van der Waals forces) Table.11.2 molecular weight,Dipole moment,and boiling point of several simple organic substances. 偶极矩 Molecular Dipole Boiling Substance Weight (amu) Moment u(D) Point(K) Propane,CH3CH2CH3 44 0.1 231 Dimethyl ether,CH3OCH3 46 1.3 248 Methyl chloride,CH3Cl 50 1.9 249 Acetaldehyde,CH3CHO 44 2.7 294 Acetonitrile,CH3CN 41 3.9 355 If two molecules have about the same mass and size,then dipole-dipole forces increase with increasing polarity. 极性
Intermolecular Forces I (van der Waals forces) Table. 11.2 molecular weight, Dipole moment, and boiling point of several simple organic substances. 偶极矩 If two molecules have about the same mass and size, then dipole-dipole forces increase with increasing polarity. 极性
Intermolecular Forces I (van der Waals forces) 偶极矩 Dipole moment and boiling point. 400 392 355 350 豆 300 294 269 250 249 249 231 200 187 150 130 100 8 0 Propane Dimethyl ether Methyl chloride Acetaldehyde Acetonitrile CH CH CH CH OCH CH CI CH CHO CH CN 44.09g/mol 46.07g/mal 50.48g/mol 44.05g/mol 41.05g/mol 。 。雪学■ 。海。 FIGURE 11.7 Dipole moment and boiling point.For compounds with similar molar masses,the boiling point increases with increasing dipole moment.The greater dipole moment creates stronger dipole-dipole forces,which require higher temperatures to overcome
Intermolecular Forces I (van der Waals forces) Dipole moment and boiling point. 偶极矩 ---- ---- ---- ---- ----