Experimental study of the isochoric heat capacity and coexistence-curve singular diameter of sec-butanol near the critical point and Yang-Yang anomaly strength

One- and two-phase isochoric heat capacities ( ) and saturated liquid and vapour densities ( , and ) of sec-butanol near the critical point have been measured with a high-temperature and high-pressure nearly constant-volume adiabatic calorimeter. The measurements were made in the temperature range from 307 K to 551 K for 22 liquid and vapour isochores from 76.44 to 794.06 kg m−3. The isochoric heat capacity jump (quasi-static thermograms supplemented by the sensor of adiabatic control) technique have been used to accurately measure of the phase transition parameters ( ) near the critical point. The total experimental uncertainty of density ( ), temperature ( ) and isochoric heat capacity ( ) measurements were estimated to be 0.06%, 15  mK and 2–3%, respectively. The critical temperature (  = 535.95 ± 0.02 K) and the critical density (  = 276.40 ± 2 kg m−3) for sec-butanol were determined from the measured saturated properties ( ,  ) near the critical point. The measured and saturated density ( ) data near...