STUDY OF THE EQUATION OF STATE OF LIQUID 2,3-DIMETHYLBUTANE AT HIGH-PRESSURES

An expansion apparatus has been used to measure the density of liquid 2,3-dimethylbutane, from 208 to 298 K and pressures up to 110 MPa. The experimental results have been used to calculate the isothermal compressibility and thermal expansion coefficient in the compressed-liquid region. Especially interesting is the behavior shown by the thermal expansion coefficient at high pressures, presenting an intersection of the isotherms at a single point. The results are compared and discussed with others from literature. The ability of two semiempirical equations of state (Deiters and BACK) to fit the data as well as to predict high-pressure results, vapor-liquid equilibrium, and derived properties along the coexistence curve has been tested.