guder_2009
==========

C\. Guder and W\. Wagner, "A Reference Equation of State for the Thermodynamic Properties of Sulfur Hexafluoride \(SF6\) for Temperatures from the Melting Line to 625 K and Pressures up to 150 MPa", J\. Phys\. Chem\. Ref\. Data 38, 33 \(2009\)

`Source record <https://github.com/LupoLab/optmat/blob/main/src/optmat/data/sources/guder_2009.toml>`__ · :doc:`Catalogue </the-data/sources>` · :doc:`Review register </register>`

DOI: `10\.1063/1\.3037344 <https://doi.org/10.1063/1.3037344>`__

**Source kind:** fit

**Recorded technique:** A reference Helmholtz\-energy equation of state for sulfur hexafluoride from the melting line to 625 K and 150 MPa, fitted to selected thermodynamic data, with an ideal\-gas part fitted to statistical\-mechanics heat capacities\.

**Materials in structured entries:** SF6

**Dataset quantities:** None recorded.

**Contents:** 0 datasets; 1 formula.

Curation notes
--------------

Identity VALIDATED\_WITH\_WARNINGS by the library\: its text layer has 269 unmapped glyphs, and the tables of pdf pp\. 25 and 39\-58 are not certified by the extraction\. Nothing is taken from those pages\. Pages cited are pdf pages\.

IDEAL GAS AND CONSTANTS\: M = 146\.0554192 g/mol \(Loss et al\. 2003\) and R = 8\.314472 J/\(mol K\) \(pdf p\. 60\); T\_c = 318\.7232 K\. The ideal\-gas heat capacity \(Eq\. 15, pdf p\. 21; Table 21, pdf p\. 22, checked against the table image\) is c\_p0/R = 1 \+ n3 \+ sum\_{i=4}^{6} n\_i \(theta\_i tau\)^2 exp\(theta\_i tau\)/\(exp\(theta\_i tau\) \- 1\)^2, tau = T\_c/T, with n3 = 3, n4\.\.n6 = 3\.661182320, 7\.878851030, 3\.459816790 and theta4\.\.theta6 = 1\.617282065, 2\.747115139, 4\.232907175\. It reproduces its input data to 6000 K within 0\.001 %\.

AGAINST COOLPROP 8\.0\.0 \(reference key Guder\-JPCRD\-2009\)\: the same M and R, and Eq\. \(15\) to 2e\-16 at 230\-625 K \(computed 2026\-09\-30\)\.

**Recorded bibliographic identity status:** VALIDATED\_WITH\_WARNINGS. This concerns identification of the source; it does not establish the scientific correctness of its contents.

Datasets
--------

No datasets are recorded.

Formulas
--------

guder\_2009/eq15
~~~~~~~~~~~~~~~~

.. code-block:: text

   {
     "id": "eq15",
     "material": "SF6",
     "equation": "Eq. (15), pdf p. 21; Table 21, pdf p. 22",
     "printed": "c_p0/R = 1 + n3 + sum_{i=4}^{6} n_i (theta_i tau)^2 exp(theta_i tau)/(exp(theta_i tau) - 1)^2",
     "variable": "tau = T_c/T, T_c = 318.7232 K",
     "range": "the melting line to 625 K",
     "coefficients": {
       "n3": "3.000000000",
       "n4": "3.661182320",
       "n5": "7.878851030",
       "n6": "3.459816790",
       "theta4": "1.617282065",
       "theta5": "2.747115139",
       "theta6": "4.232907175",
       "critical_temperature": "318.7232"
     },
     "check": "CoolProp 8.0.0 equals it to 2e-16 (tests/test_transport.py)."
   }

Corrections
-----------

No dataset errata are recorded in this source record.

Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the :doc:`review register </register>` for the checks and decisions.