Approximations can help to orient the student in an organic chemistry laboratory. There the student needs to develop the solvent systems for the reaction and isolation of organic reactants and products. The adage "like dissolves like" helps in this regard, but this approach is vague and entirely qualitative. More quantitative approaches have been developed, but these methods require special information about the solute's properties. By examining water solubilities for various monofunctional molecules, a semiquantitative device based solely on the solute's number of carbons has been found to deliver a useful estimate of aqueous solubility for various uncharged organic chemicals.