化學...分散力係唔係只在非極性分子中出現?

van der Waals' forces includes different types of dipole interactions.


(1) dipole-dipole interactions(偶極–偶極力)
(2) dipole-induced dipole interactions(偶極–誘導偶極力)
(3) instantaneous dipole-induced dipole interactions(分散力)



dipole-dipole interactions: polar molecules + polar molecules
dipole-induced dipole interactions: polar molecules + non-polar molecules
instantaneous dipole-induced dipole interactions: all molecules



分散力唔一定只在非極性分子中出現
因為佢存在於所有分子，唔理係POLAR/ NON-POLAR。



或者再解釋清楚d



Boiling point:
CH3CH2CH2CH2CH2Cl: 381 K
CH3CH2CH2CH2CH2CH3: 371.5 K



你可以見到CH3C H2C H2C H2C H2C H3 呢個non-polar molecule 個b.p係371.5K.
而CH3C H2C H2C H2C H2C H3 主要靠dispersion forces.

之後再睇下CH3C H2C H2C H2C H2C l呢個polar molecule個b.p係381 K
因為本身CH3C H2C H2C H2C H2C H3 呢個non-polar molecule 個b.p都有371.5K
可想言之，CH3C H2C H2C H2C H2C l唔可以單單靠 dipole-dipole interactions 而能夠有咁強既吸力做出b.p 去到381K ，所以可推斷出分散力唔一定只在非極性分子中出現。