Solubility of ibuprofen. Ibuprofen is a large non-polar molecule which is insoluble in water in its molecular form. The molecular form of ibuprofen reacts as a carboxylic acid and will form a water-soluble salt upon its reaction with sodium carbonate solution. The sodium salt of ibuprofen is water-soluble due to the newly acquired ability to form stronger intermolecular forces (ion-dipole) with polar water molecules.