The most likely interaction to be found in an aqueous solution of ethanol is

A. London dispersion forces
B. Hydrogen bonding
C. Dipole-dipole interactions
D. Ion-dipole interactions

I am split between B and C. I actually thought it was both of them but the question requires me to choose only one.

  • 4
    $\begingroup$ I really think the question is poorly worded. The phrase "most likely" is a probability consideration. The only answer that is really eliminated is (d) since few of the water molecules will be ionized. HINT - The only way to answer the question is to think of "most likely" to mean "most significant," that is the strongest type of bonding from the remaining three. So what do you think? $\endgroup$ – MaxW Sep 14 '16 at 2:12

(A) is out as London dispersion (instantaneous dipole-induced dipole) forces are weak, always present, and do not contribute much to the main intermolecular forces of attraction.

(D) is out as auto-ionisation of water $$\ce{2H2O -> H3O+ + OH-}$$ is negligible.

That leaves (B) and (C).

ethanol water

Looking at their structures, hydrogen bonding will be the more dominant force as the Hs highlighted in the structures can be exposed to hydrogen bonding.

  • 2
    $\begingroup$ Some comments. (1) It isn't just about the right answer. This about the chemistry too. (2) Your answer doesn't really address the poor wording of the question. (3) In the last paragraph, hydrogen bonding involves more than just hydrogen atoms. In this case hydrogen bonding will be hydrogen atoms from one molecule to the oxygen atom on the other. $\endgroup$ – MaxW Sep 14 '16 at 3:14

All the lower alcohols are soluble in water due to hydrogen bonding(the compounds which can form hydrogen bond with the solvent molecules are soluble in such solvents).since ethanol is an alcohol thus it is bonded with water molecule by hydrogen bond.see the bond between an alcohol and water in the pictureenter image description here


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