Tristearin and stearic acid are insoluble in water. however, sodium stearate (soap) is soluble. why is there this difference in solubility?

Explanation:

Sodium stearate , is the soap , it a ionic compound , hence , can easily break to cation and anion , and therefore is soluble in water .It works on the principle of micelle formation .

Tristearin and stearic acid are fatty acids , and have are carboxyl group and have a very huge hydrocarbon chain , making it non polar in nature ,hence is is insoluble in water , since , water is a polar molecule .