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I am completing a project on gallium, and I need to include its boiling point. I thought that this would be fairly simple to look up, however, it appears that different sources quote different temperatures as the boiling point, normally either ~2200 °C or ~2400 °C.

Does anyone know why two different values are presented, or which value is correct?

Below are some examples of websites quoting each figure.

2200 °C:

https://education.jlab.org/itselemental/ele031.html

http://www.rsc.org/periodic-table/element/31/gallium

https://www.livescience.com/29476-gallium.html

2400 °C:

http://www.chemistryexplained.com/elements/C-K/Gallium.html

https://www.britannica.com/science/gallium

http://www.chemicalelements.com/elements/ga.html

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    $\begingroup$ Wikipedia cites 2400 from researchgate.net/publication/… which is article wholly about getting good values. $\endgroup$ – Mithoron Nov 2 '17 at 21:07
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    $\begingroup$ In order to help solve this discrepancy, it may be useful to source a graph/equation of vapour pressure versus temperature and find the temperature for a pressure of 1 bar. It is far easier to type an incorrect number than produce an incorrect graph/equation, plus whoever made the graph/equation probably put some effort into ensuring its accuracy. $\endgroup$ – Nicolau Saker Neto Nov 2 '17 at 22:12
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This question has been recently raised in Chemistry & Engineering Letters. The CRC Handbook (2017) in section "MELTING, BOILING, TRIPLE, AND CRITICAL POINTS OF THE ELEMENTS" [1, p. 4-117] lists the following values for gallium, quoting original publication [2]:

\begin{align} t_\mathrm{tp} (\ce{Ga}) &= \pu{29.7666 ^\circ C} \\ t_\mathrm{m} (\ce{Ga}) &= \pu{29.7646 ^\circ C} \\ t_\mathrm{b} (\ce{Ga}) &= \pu{2229 ^\circ C} \\ \end{align}

[...] values are given for the solid-liquid-gas triple-point temperature $t_\mathrm{tp}$ and pressure $p_\mathrm{tp}$; normal melting point at $\pu{101.325 kPa}$ pressure $t_\mathrm{m}$; normal boiling point $t_\mathrm{b}$; and critical temperature $t_\mathrm{c}$ and pressure $p_\mathrm{c}$. All temperatures are on the ITS-90 scale.

References

  1. Haynes, W. M.; Lide, D. R.; Bruno, T. J. CRC Handbook of Chemistry and Physics: A Ready-Reference Book of Chemical and Physical Data.; 2017; Vol. 97. ISBN 978-1-4987-5429-3.
  2. Geiger, F.; Busse, C. A.; Loehrke, R. I. Int J Thermophys 1987, 8 (4), 425–436 DOI: 10.1007/BF00567103.
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  • $\begingroup$ I was hoping someone would check the CRC handbook... $\endgroup$ – NH. Nov 2 '17 at 23:25
  • $\begingroup$ @NH CRC Handbook is also handy when it comes to pinpointing up-to-date source of information, at least in the majority of cases:) $\endgroup$ – andselisk Nov 2 '17 at 23:30
  • $\begingroup$ We always had a copy of the CRC handbook in our undergrad physics labs as our go-to source. $\endgroup$ – Mick Nov 3 '17 at 0:54
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    $\begingroup$ You've got twice as much "recently" in the first sentence as you need :) $\endgroup$ – hobbs Nov 3 '17 at 3:01
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    $\begingroup$ The comments section in the C&E letters addresses why this discrepancy existed. $\endgroup$ – Tyberius Nov 3 '17 at 3:23

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