Question

In preparation for your distillation, you performed an extraction on your oil/vinegar salad dressing mixture. Why does cooking oil dissolve in ethyl acetate, but not water?

Answer 1

Answer : Oil is non-polar while water is polar. Oil will not dissolve in water because water is a polar molecule and as a non-polar molecule oil is hydrophobic. Because oil molecules are not polar, the forces between oil and water are not strong enough to break the polar bonds between water molecules which is why oil will not mix with water. Oil will dissolve in ethyl acetate because it is also non-polar and thus the bonds between oil and ethyl acetate molecules are stronger than the forces between their interactions with their own molecules allowing them to mix.

Like dissolves like. A polar substance will not dissolve a nonpolar substance. In the case of oil and vinegar, the vinegar is polar and more dense than the oil, so it settles on the bottom of the container. The oil is nonpolar and less dense, so it doesn't dissolve in the vinegar, and it floats on top.