A 1:1 mixture of 2-butanone and water forms two layers
CHEMISTRY · Single correct · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A 1:1 mixture of 2-butanone and water forms two layers. After a small amount of ethanol is added and the mixture is shaken, a single clear phase results. Which statement most likely accounts for the disappearance of the phase boundary?
(a) Ethanol lowers the density of the organic layer, allowing it to disperse into water.
(b) Ethanol acts as a surfactant, surrounding 2-butanone molecules in micelle-like structures that keep them suspended in water.
(c) Ethanol forms hydrogen bonds with both 2-butanone and water, lowering the overall free-energy of mixing so all three substances become miscible.
(d) Ethanol reacts with 2-butanone to produce a water-soluble product, eliminating the phase boundary.