Thermodynamic Properties of Aqueous Solution of 2-Isopropoxyethanol at 25°C

Abstract

Excess enthalpy, excess isobaric heat capacity, density, and speed of sound for aqueous 2-isopropoxyethanol solutions were measured at 25°C. The density was also measured at 20°C. The excess enthalpy was −800 J-mol⁻¹ at the minimum (mole fraction alcohol, x = 0.2), showing that the hydrogen bonds formed between unlike molecules are stronger than those in both pure liquid states. The excess volume also was large and negative, more than −1.2 cm³-mol⁻¹ at the minimum (x = 0.35). Excess isentropic and isothermal compressibilities are extremely negative. These results suggest that breaking the hydrogen bond network in water and forming the stronger hydrogen bonds between unlike molecules reduces the volume of the solution and makes the solution less compressible. The excess isobaric heat capacity is positive and large, up to 10 J-K⁻¹-mol⁻¹ and shows anomalous behavior in the neighborhood of x = 0.15.