Thermodynamics of complexation of aqueous 18-crown-6 with potassium ion: apparent molar volumes and apparent molar heat capacities of aqueous 18-crown-6 and of the (18-crown-6 + potassium chloride) complex at temperatures (278.15 to 393.15) K, at molalities (0.02 to 0.3) mol . kg-1, and at the pressure 0.35 MPa

We have measured the densities at temperatures T = (278.15 to 363.15) K and heat capacities at T = (278.15 to 393.15) K of aqueous solutions of 18-crown-6 and of (18-crown-6 + KCl) at molalities m = (0.02 to 0.3) mol . kg-1 and at the pressure 0.35 MPa. We have calculated apparent molar volumes Vφ and apparent molar heat capacities Cp,φ for 18-crown-6(aq), and we have applied Young's Rule and have accounted for chemical speciation and relaxation effects to resolve Vφ and Cp,φ for the (18-crown-6: K+,Cl-)(aq) complex in the mixture. We have also calculated estimates of the change in volume ΔrVm, the change in heat capacity ΔrCp,m, the change in enthalpy ΔrHm, and the equilibrium quotient log Q for formation of the complex at T = (278.15 to 393.15) K and m = (0 to 0.3) mol . kg-1