An unknown molecular compound X has the empirical formula C₃H₆O. The compound is tested for solubility at room temperature in three solvents of comparable polarity index:
• Water – complete miscibility
• Ethanol – complete miscibility
• n-Hexane – negligible solubility (two layers form)
Assume X does not ionize in any solvent.
(a) Based solely on the solubility data, identify the dominant type(s) of intermolecular force acting between molecules of X and water. Explain your reasoning.
(b) Two structural isomers that match the empirical formula are shown below in condensed form:
I. CH₃–CH₂–CHO (propanal)
II. CH₃–CO–CH₃ (propanone, commonly called acetone)
Using intermolecular-force arguments, determine which structure more plausibly corresponds to compound X. Support your choice with at least two pieces of evidence derived from the solubility observations.
(c) Sketch or describe a particulate-level diagram that depicts one molecule of your chosen structure interacting with two water molecules. Indicate the orientation of the water molecules and label any hydrogen bonds or dipole–dipole interactions.