The aspirin molecule is made up of a benzene ring, a carboxyl group, and an ester. It has both polar and non-polar components. Thus, the affinity of water (very polar) for this compound is not as great as the affinity of water for itself. However, the affinity of ethanol molecules (only slightly polar) for aspirin molecules is relatively similar to the affinity of ethanol molecules for each other. Thus, aspirin is more soluble in ethanol than in water.