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. $\endgroup$ Commented Nov 16, 2017 at 8:47
  • 2
    $\begingroup$ KCl is a formula unit. $\endgroup$
    – andselisk
    Commented Nov 16, 2017 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
    Commented Aug 10, 2019 at 7:32

2 Answers 2


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.


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

  • 2
    $\begingroup$ This is wrong because K+ is hydrated as stated in the question. There are indeed IMFs for ions in solution. Ion-dipole forces and LDF will dominate. $\endgroup$ Commented Dec 8, 2019 at 3:11
  • 1
    $\begingroup$ So an ion acts like an ideal gas in a solution??? $\endgroup$
    – B. Kelly
    Commented Dec 8, 2019 at 3:48

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