Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Molar Heat Capacity at Constant Volume for Isobutane at Temperatures from (114 to 345) K and at Pressures to 35 MPa

Perkins, R. A.[Richard A.], Magee, J. W.[Joseph W.]
J. Chem. Eng. Data 2009, 54, 9, 2646-2655
ABSTRACT
Molar heat capacities at constant volume (C_v) were measured with an adiabatic calorimeter for pure isobutane. The high purity of the samples was verified by chemical analysis. Temperatures ranged from the triple point of isobutane near 114 K to the upper temperature limit of the calorimeter at 345 K, whereas pressures ranged up to 35 MPa. Measurements were conducted on liquid in equilibrium with its vapor and on compressed liquid samples along isochores. Heat capacity results are reported for two-phase (C_v(2)), saturated liquid (C_sat), and single-phase (C_v) isochores. Vapor pressure data are reported that are based on measurements of C_v(2) along a two-phase isochore. Measurements were also made to determine the triple-point temperature of (113.707 +/- 0.030) K and enthalpy of fusion of (4494 +/- 20) J*mol-1 for isobutane near its triple point. The principal sources of uncertainty are the temperature rise measurement and the change-of-volume work adjustment. The expanded uncertainty (i.e., a coverage factor k = 2 and thus a two-standard deviation estimate) for values of C_v(2) is estimated to be 0.5 %, for C_sat it is 0.7 %, and for C_v it is 0.7 %.
Compounds
# Formula Name
1 C4H10 2-methylpropane
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 1
  • Molar enthalpy of transition or fusion, kJ/mol ; Crystal
  • Crystal
  • Liquid
  • Gas
  • Adiabatic calorimetry
  • 1
  • POMD
  • 1
  • Triple point temperature, K ; Crystal
  • Crystal
  • Liquid
  • Gas
  • Adiabatic calorimetry
  • 1
  • POMD
  • 1
  • Molar heat capacity at saturation pressure, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Gas
  • Vacuum adiabatic calorimetry
  • 93
  • POMD
  • 1
  • Molar heat capacity at constant volume, J/K/mol ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • Vacuum adiabatic calorimetry
  • 171
  • POMD
  • 1
  • Amount density, mol/m3 ; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Liquid
  • ISOCHOR
  • 171
  • POMD
  • 1
  • Vapor or sublimation pressure, kPa ; Liquid
  • Temperature, K; Liquid
  • Liquid
  • Gas
  • Derived from internal energy loop calculations
  • 75