Effects of Different Solvent Characteristics on the Proton-Ligand and Ni2+-, Sm3+-, AND Yb3+- Ligand Formation Constants of 5,5-Dimethyl-Cyclohexane-2-(2-Hydroxyphenyl)Hydrazono- 1,3-Dione (DCPHD) in Various Mixed Aqueous Solvents-(II)

Complex equilibria of DCPHD with proton and Ni²⁺, Sm³⁺, and Yb³⁺ ions has been measured in various mixed aqueous solvents, viz: isopropanol-water, acetone-water, ethanol-water, and methanol-water. Based on potentiometric equilibrium measurements of hydrogen ion concentration at 30°C, ionic strenght 0.10 M (KNO₃) and in the above various mixed aqueous solvents, the values of the protonation constants of DCPHD and the stability constants of DCPHD with Ni²⁺, Sm³⁺, and Yb³⁺ have been evaluated. The variation of protonation and stability constants with the inverse of dielectric constant or mole fraction of the solvent was studied. Application of Fuoss expression and consideration of electrosatic and non-electrostatic effects are made to explain the values of the constants.