I want to study the intermolecular forces (IMFs) in hydrated potassium ion, $\ce{K+ (aq)}$ in an aqueous solution of $\ce{KCl}$. According to my thoughts, among the 4 IMFs I know:

  • London dispersion forces (LDFs);
  • Dipole-Dipole interaction;
  • Hydrogen bonding;
  • Ion-dipole forces

LDFs are definitely included, but my question is whether dipole-dipole is included as well (because KCl is a polar substance)?

  • 3
    $\begingroup$ KCl is not a molecule at all. $\endgroup$ – Ivan Neretin Nov 16 '17 at 8:47
  • 2
    $\begingroup$ KCl is a formula unit. $\endgroup$ – andselisk Nov 16 '17 at 8:51
  • $\begingroup$ K+ is a spherical ion. The water molecule has a dipole. So which do you think are relevant? $\endgroup$ – Ian Bush Aug 10 at 7:32

There are no intermolecular forces in KCl because it is an ionic compound. IMFs only exist in covalent compounds between molecules.


Dipole-dipole interaction, specifically, will probably not happen, or they at least won't contribute significantly to IMFs. The thing with these different chemical bonds is that they are mostly based in identical features, and sometimes calculated differently, taking different things in account.
An ionic bond will be stronger than a polar bond, so that is why dipole-dipole interaction seems irrelevant, in comparison to ion-dipole forces.

All the kinds of interaction mentioned are derivatives of electrostatic interaction, also know as Coulomb interaction. LDFs are a direct derivative of Van der Waals bonds, but if you look more physically at all those bonds you can think of them as electrostatic interaction.


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