Abstract
Specific heat capacity at constant volume is one of the most important thermodynamic properties to develop and evaluate thermodynamic equations of state. With this viewpoint, isochoric heat capacities of ethanol-water mixtures have beenmeasured with a twin-cell type adiabatic calorimeter developed at the National Defense Academy. Temperatures were measured with a platinum resistance thermometer on the bottom of each cell and were reported on the ITS-90. Sample pressure measurements were made with a quartz crystal transducer. Densities were calculated from the volume of the calorimeter cell and sample mass. The experimental expanded uncertainty (with a coverage factor k=2)of temperature measurements is ±13mK, and that of pressure measurement is ±8kPa. The expanded relative uncertainty for isochoric heat capacity is estimated to be ±2% for liquid phase measurements, and for density it is ±0.16%. The present measurements for {xC2H5OH + (l-x)H2O} with x=(0.104, 0.253, 0.498 and 0.755), were obtained at temperatures from 280 to 420 K and at pressures up to 30 MPa.
