Calorimetric investigation of excess molar heat capacities for water plus ethylene glycol from T=273.15 to T=373.15 K

The molar excess heat capacity C-p(E),m of (1-x)H2O + xHOCH(2)CH(2)OH has been measured in the temperature range from 273.15 K to 373.15 K at 5 K intervals. The C-p(,m)E values are negative and positive at all compositions between temperatures of (273.15, 283.15, 333.15 and 373.15) K, respectively. Between T = 288.15 K and T = 328.15 K, C-p(E) in values are positive for the mixtures rich in water and negative for the mixtures rich in ethylene glycol with maxima at values of x about 0.07, 0.3 and with minima at values of x about 0.6. The curve of C-p(,m)E against x at T = 303.15 K is unusual in showing three maximum values at values of x at about 0.07, 0.3, and 0.4, respectively. The curves of C-p(,m)E against T show that the effects of T on C-p(,m)E at x 0.5372, and 0.7232 are more complex. The shapes of the curves of C-p(,m)E against x and their changes with temperature can be accounted for by the structure of the binary system. (C) 2002 Elsevier Science Ltd. All rights reserved.