Nonpolar solvents such as hexane, C6H14, generally are immiscible with water, thus, when water and hexane are placed together in the same container, they will separate into two layers as shown below. Hexane, density=0.69 g/mL, will form the top layer.
Some substances are soluble in both solvents, to differing extents. Consider the following organic acids, all of which exhibit some ability to dissolve in both water and in hexane.
Ethanoic acid, CH3COOH, propanoic acid, CH3CH2COOH, butanoic acid, CH3CH2CH2COOH, and pentanoic acid, CH3(CH2)3COOH.
A student designs an experiment to determine the relative solubilities of the four acids in hexane and in water. She wants to express her results in the form of a ratio, represented by k, defined as follows.