P–ρ–TData and Derivative Properties of 3-Methylpentane, 2,4-Dimethylpentane, and 2,3,4-Trimethylpentane from 283.15 to 363.15 K at Pressures up to 65 MPa

Abstract

In this work, we present densities at high pressures of three branched hydrocarbons: 3-methylpentane, 2,4-dimethylpentane, and 2,3,4trimethylpentane from 283.15 to 363.15 K and at pressures up to 65 MPa. We have used a vibrating tube densimeter along with the forced path calibration method. This method considers mechanical properties of the cell and allows us to reach standard uncertainties less than 0.0004 g•cm 3 . For 3methylpentane, the new density data agree within 0.2% with densities from the literature. For the case of 2,4-dimethylpentane and 2,3,4-trimethylpentane, densities at high pressures have not been reported in the literature. Isobaric expansibility and isothermal compressibility are calculated using an equation of state correlated to the experimental density data.

P–ρ–T Data and Derived Volumetric Properties of Benzyl Alcohol, ±2-Octanol (Racemic Mixture), and 1-Heptanol from 283.15 to 363.15 K at Pressures up to 65 MPa

“…The last five quantities are functions of temperature and pressure, and the last two are also evaluated at vacuum (P 0 ). The correction of the tube length with temperature and pressure is and the oscillating period at vacuum ,, is expressed by In the above equation, a i denotes fitting parameters. Laznickova and Huemer point out that the oscillating period at vacuum depends upon temperature and time ( t ).…”

“…The radii differences in eq are defined as The subscripts i and e indicate the internal and external radiuses of the vibrating tube, respectively, and the subscript 0 refers to the vacuum. The calculation of r e and r i is done using , where P ref is the reference pressure; in this work, P ref = 0.0824 MPa was used, and the expression for the radius at vacuum is given by , where T ref is a reference temperature equal to 293.15 K, and the values for the reference radiuses at vacuum are r i 00 = 0.1073 cm and r e 00 = 0.1588 cm. The linear dilatation coefficient in eq is given by a cubic polynomial in temperature, In eq , ν is the Poisson’s coefficient, which is considered temperature-independent with a value equal to 0.307, and E is the Young’s modulus given by Then, the calibration parameters M 0 / L 0 , γ, and a i are obtained from a simultaneous correlation of eqs and to the experimental data of the oscillation period at vacuum and the oscillation period of water from 283.15 to 363.15 K and pressure up to 65 MPa.…”

“…The isothermal compressibility (κ T ) is defined as and in terms of Helmholtz energy, it is A property related to the isothermal compressibility is the isobaric expansibility or thermal expansion coefficient (α P ), which is related through Expressing the derivative of eq in terms of Helmholtz energy The derivatives of the residual Helmholtz function in eqs and are given in the Supporting Information. In this work, we have calculated the thermal expansion coefficient (α P ) and the isothermal compressibility (κ T ) using eq together with eqs and .…”

“…where P ref is the reference pressure; in this work, P ref = 0.0824 MPa was used, and the expression for the radius at vacuum is given by 34,35 r r T T j i e exp ( )d for ,…”