Compound Information 

Name: hydrogen iodide
Formula: HI
Molar Mass: 127.91247
Additional Names: anhydrous hydriodic acid
hydriodic acid
hydroiodic acid
hydrogen monoiodide
hydrogen iodide (HI)
Image of hydrogen iodide

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Property Availability 

For this compound, WTT contains critically evaluated recommendations for:
(Please note that if more than 50 points are used for regression, only the 50 most-constraining points are reported)

  • Triple point temperature
    • Triple point temperature (Crystal 1, Liquid, and Gas)
      2 experimental data points
    • Triple point temperature (Crystal 3, Crystal 2, and Gas)
      1 experimental data points
    • Triple point temperature (Crystal 2, Crystal 1, and Gas)
      1 experimental data points
  • Phase boundary pressure (Crystal 1 in equilibrium with Gas) as a function of Temperature
    Temperature from 168.231 K to 222.506 K
    42 experimental data points
    • Enthalpy of phase transition
      • Enthalpy of phase transition (Crystal 3 to Crystal 2 in equilibrium with Gas)
        2 experimental data points
      • Enthalpy of phase transition (Crystal 1 to Liquid in equilibrium with Gas)
        1 experimental data points
      • Enthalpy of phase transition (Crystal 2 to Crystal 1 in equilibrium with Gas)
        1 experimental data points
    • Enthalpy of vaporization or sublimation (Crystal 1 to Gas) as a function of Temperature
      Temperature from 168.231 K to 222.506 K
      • Heat capacity at saturation pressure
        • Heat capacity at saturation pressure (Crystal 3 in equilibrium with Gas) as a function of Temperature
          Temperature from 4 K to 70.23 K
          50 experimental data points
        • Heat capacity at saturation pressure (Crystal 2 in equilibrium with Gas) as a function of Temperature
          Temperature from 70.23 K to 125.614 K
          50 experimental data points
        • Heat capacity at saturation pressure (Crystal 1 in equilibrium with Gas) as a function of Temperature
          Temperature from 125.614 K to 222.506 K
          44 experimental data points
      • Heat capacity at constant pressure (Ideal Gas) as a function of Temperature
        Temperature from 50 K to 3000 K
        • Enthalpy
          • Enthalpy (Crystal 3 in equilibrium with Gas) as a function of Temperature
            Temperature from 4 K to 70.23 K
          • Enthalpy (Crystal 2 in equilibrium with Gas) as a function of Temperature
            Temperature from 70.23 K to 125.614 K
          • Enthalpy (Crystal 1 in equilibrium with Gas) as a function of Temperature
            Temperature from 125.614 K to 222.506 K
            22 experimental data points
          • Enthalpy (Ideal Gas) as a function of Temperature
            Temperature from 50 K to 3000 K
        • Entropy
          • Entropy (Crystal 3 in equilibrium with Gas) as a function of Temperature
            Temperature from 4 K to 70.23 K
          • Entropy (Crystal 2 in equilibrium with Gas) as a function of Temperature
            Temperature from 70.23 K to 125.614 K
          • Entropy (Crystal 1 in equilibrium with Gas) as a function of Temperature
            Temperature from 125.614 K to 222.506 K
          • Entropy (Ideal Gas) as a function of Temperature and Pressure
            Temperature from 50 K to 3000 K
        • Viscosity (Liquid in equilibrium with Gas) as a function of Temperature
          Temperature from 223.338 K to 236.429 K
          7 experimental data points

          About WTT 

          NIST/TRC Web Thermo Tables (WTT)
          NIST Standard Reference Subscription Database 3 - Professional Edition
          Version 2-2012-1-Pro

          This web application provides access to a collection of critically evaluated thermodynamic property data for pure compounds with a primary focus on organics. These data were generated through dynamic data analysis, as implemented in the NIST ThermoData Engine software package [1, 2, 3, 4, 5, 6]. Some critically evaluated data from the historical TRC Thermodynamic Tables archive [7, 8] are included, also. As of May 2012, the Professional Edition contains information on 28432 compounds and total of 531486 evaluated data points. The properties covered by both versions (32 total) are described in Properties and Implemented Models.

          Developed by Kenneth Kroenlein, Chris D. Muzny, Andrei F. Kazakov, Vladimir Diky, Robert D. Chirico, Joseph W. Magee, Ilmutdin Abdulagatov and Michael Frenkel.

          Thermodynamics Research Center (TRC)
          Thermophysical Properties Division
          National Institute of Standards and Technology
          Boulder CO 80305-3337

          Questions and comments should be addressed to Dr. Michael Frenkel .

          DISCLAIMER: The National Institute of Standards and Technology (NIST) uses its best efforts to deliver a high-quality copy of the database and to verify that the methods and data contained therein have been selected on the basis of sound scientific judgement. However, NIST makes no warranties to that effect, and NIST shall not be liable for any damage that may result from errors or omissions in the program and database.

          Distributed by:
          Standard Reference Data Program
          National Institute of Standards and Technology
          Gaithersburg MD 20899

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