Question about hydrogen bond 2

2007-03-14 9:59 pm
The intermolecular attraction between HCl only count as Van der Waals forces, if it is because the electron cloud is too diffuse for Cl to form a powerful dipole, yet the dipole dipole attraction will be too weak to form hydrogen bond, then why is that for HCCl3 and CCl4, the intermolecular attraction include hydrogen bond?

回答 (2)

2007-03-15 1:47 am
✔ 最佳答案
CCl4 can't form hydrogen bond but hydrogen bonding is possible for CHCl3

formation of hydrogen bonding requires 2 criteria:
1) the lone pair electrons of 3 most electronegative elements, N, O, F. ( the lone pair electrons of N, O, F atoms are compact. )
2) a hydrogen atom which is bonded with 1 of the 3 most electronegative elements.

obviously, CCl4 cannot form hydrogen bond. Besides, tetrachloromethane is a non-polar molecule. the intermolecular force within CCl4 molecule is van der waal's force, instantaneous dipole induced dipole interaction.

CHCl3 cannot form hydrogen bond with another CHCl3 molecule but it can form hydrogen bond with species contain lone pair electrons of N, O, F elements.
eg. H2O, NH3, HF, aldehyde, ketone, alcohol, ether, amine or even various pharmaceutical compounds.
This is due to the C atom of CHCl3 molecule is bonded to 3 chlorine atoms. As Cl atom is electron withdrawing from C and H atoms, making the H atom of trichloromethane highly electron deficient which is comparable with the H atom bonded with N, O or F atom.
Hence, trichloromethane (CHCl3) molecule is able to form hydrogen bond with another molecule which contains lone pair electrons of N, O, F atoms.

that's why the liquid mixture of CHCl3 and diethyl ether shows negative deviation from Raoult's law of ideal solution, forming hydrogen bonding in the mixture
參考: original
2007-03-14 10:37 pm
HCCl3 and CCl4 cannot form hydrogen bond with its molecules...
Only N, F and O can form hydrogen bond if it combines with H .


收錄日期: 2021-04-13 13:49:43
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070314000051KK01379

檢視 Wayback Machine 備份