Effect of temperature on the process of complex formation crown ether 15C5 with Na+ in the mixture of water with methanol

•The system 15C5/Na+ complex + water + methanol have been investigated.•The thermodynamic functions of 15C5/Na+ complex formation were calculated.•The enthalpy of complex formation has been calculated using calorimetric method.•The enthalpy of complex formation has been calculated from van’t Hoff’s equation.•The obtained results have been compared.

Thermodynamic functions of complex formation of 15-crown-5 ether (15C5) with sodium cation (Na+) in the mixtures of water (W) with methanol (MeOH) at different temperature have been calculated. To obtain this function two experimental methods have been used. The equilibrium constants of complex formation have been determined by conductivity measurements and the enthalpic effect of complex formation has been measured by the calorimetric method and has been also calculated using van’t Hoff’s equation. The obtained results were compared and discussed. The complexes are enthalpy stabilized but entropy destabilized.