Acetone- water & acetone-Ethanol are example of different strength of H-bonding by acetone.
Remember (1) Both water & alcohol are amphiporotic solvent , but Water is more acidic than ethanol.
(2) Acetone has a Basic doubly-bonded Oxygen,
(3) Acetone cannot form H-bond among themselves but greater dipole moment (Acetone’s dipole moment is 2.91D) & Basic oxygens of Acetone help it to form strong H-bond with either of two acidic protons of water. Thereby attractive forces gets strong.(consider hydrate formation & tautomerism to some extent as well, however they are not deciding factor here)
In fact, H-bonding of Acetone with water is more stronger than that of alcohol-water (acetone is completely miscible with water as well).
this is the reason, Alcohol- water has positive deviation but acetone-water has negative deviation
(4) the question remains why acetone -ethanol has positive deviation. If you consider its high dipole moment, its soluble in almost all organic solvents as well as water.
However, Its H-bonding with ethanol is not as strong as with water, due to greater hydrophobic part in ethanol as well as less acidic proton in ethanol./
Hence, Ethanol-water has positive deviation.
- Octane + heptane,
- ethanol + 1-butanol and
- methyl acetate + methyl acrylate are near ideal solutions.
- Methanol + acetone,
- ethanol + acetone,
- methanol + methyl acetate,
- methanol + methyl acrylate,
- isoamyl alcohol + isoamyl acetate,
- octane + 1-butanol,
- octane + 2-butanol,
- octane + ethanol,
- ethylene glycol and CCl4 and
- octane + isopropanol mixtures deviate positively from an ideal solution.
- Acetic acid and n-propanol,
- cyclohexylamine + cyclohexanol,
- phenol + acetophenone,
- phenol + cyclohexanol, and
- phenol + cyclohexanone, all deviate negatively from ideality.