Be sure to answer all parts. recall that there is restricted rotation around carbon-carbon double bonds. maleic acid and fumaric acid are two isomers with vastly different physical properties and pka values for loss of both protons. explain why each of these differences occurs. 365 fumaric acid than maleic acid, giving it a higher melting point. maleic acid is than fumaric acid, giving it greater h2o solubility. in maleic acid, stabilizes the conjugate base after one h is removed, making maleic acid more acidic than fumaric acid.