Applying fractional cohesion parameters to calculate the enthalpies of chemical denaturation revealed the forces affecting this process. We applied Hansen's concept of three-component fractional cohesive parameters to consider the influences of the dispersion or non-polar interaction, the hydrogen bonding, and the polar interaction in the analysis of the chemical denaturation of DNA. related to the orientation effect between two molecules with a permanent dipole moment. Parameters δ a and δ b are presented by authors to define nonsymmetrical electron-donor and electron-acceptor properties of two components (DNA and denaturant) with different roles. This issue has been explained in terms of Lewis acid-base cohesion parameters. The relationship among these parameters is the following: