Question

Would you expect lactic acid, ch3ch(oh)co2h ( in sour milk) or myristic acid, ch3(ch2)12co2h (used to make cosmetics) to be more soluble in water? why?

Answer 1

Among these two compounds Lactic Acid is completely soluble in water (1000 g/L) while, Myristic Acid is insoluble in water [20 mg/L (20 °C)].

Explanation:
                   Among other factors solubility greatly depends upon the inter-molecular interactions between solute and solvent (LIKE DISSOLVES LIKE). Greater the interactions greater is the solubility.
                   As shown below, Lactic Acid contains two hydroxyl groups and one carbonyl group. These three groups are involved in forming Hydrogen Bond Interactions with the molecules of Water.
                   Whereas, Myristic Acid contains a long chain of carbon which is non polar in nature. So, due to this non polar carbon chain no such interactions are formed as formed in case of Lactic Acid. Still the less solubility found is due to the interaction of Carboxylic group of Myristic Acid with water molecules, which is comparatively very less.