Excess thermodynamic properties of binary mixtures of ethyl formate with benzene, ethanol, and 2,2,2-trifluoroethan-1-ol at 298.15 K

Excess enthalpies, excess isobaric heat capacities, densities and speeds of sound of the mixtures ethyl formate + benzene, + ethanol, and + 2,2,2-trifluoroethan-1-ol, were measured at 298.15 K; the densities were also measured at 303.15 K. The excess volumes were estimated from the density, and the isentropic and isothermal compressibilities and isochoric heat capacities were estimated from the density, speed of sound and isobaric heat capacity. The HmE of the HCOOC2H5 + CF3CH2OH system changes anomalously from negative (minimum value −140 J mol−1) to positive (maximum 200 J mol−1) with the concentration of HCOOC2H5. The CP,mE is large and negative (the minimum value is −6.3 J K−1 mol−1). However, VmE, κSE and κTE for the mixture are very large but positive, and these maxima are 0.8 cm3 mol−1, 52 TPa−1, and 98 TPa−1 respectively. All of these can be attributed to the formation of unlike association and the destruction of cluster structure in pure CF3CH2OH by mixing, and the breakage of intermolecular association of HCOOC2H5. The HmE and CP,mE of HCOOC2H5 + C2H5OH are large and positive, and their maximum values are about 1380 J mol−1 and 9.2 J K−1 mol−1. However, the VmE, κSE and κTE are very small. Comparing with the mixture of CH3COOC2H5 + C6H6 reported before, the HmE (maximum 350 J mol−1) and VmE (maximum 0.29 cm3 mol−1) of the HCOOC2H5 + C6H6 system are apparently larger, although the CP,mE, κSE and κTE are also very small.