Glenbrook rail accident and Tungsten hexafluoride: Difference between pages

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The '''Glenbrook train disaster''' was a [[railway]] accident in [[New South Wales]], [[Australia]] on [[December 3]] [[1999]]. It happened on a curve of track east of Glenbrook station on the [[CityRail]] network between [[Springwood, New South Wales|Springwood]] and [[Penrith, New South Wales|Penrith]].

! {{chembox header}} | Tungsten(VI) fluoride

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| align="center" colspan="2" | [[Image:Tungsten-hexafluoride-3D-balls.png|100px|Ball-and-stick model of tungsten hexafluoride]] [[Image:Tungsten(VI) fluoride.jpg|100px|Tungsten(VI) fluoride]]

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! {{chembox header}} | General

|-

| [[IUPAC nomenclature|Systematic name]]

| Tungsten(VI) fluoride

|-

| Other names

| Tungsten hexafluoride

|-

| [[Chemical formula|Molecular formula]]

| WF₆

|-

| [[Molar mass]]

| 297.83 g/mol

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| Appearance

| Colorless gas.

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| [[CAS registry number|CAS number]]

| {{CASREF|CAS=7783-82-6}}

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! {{chembox header}} | Properties

|-

| [[Density]] and [[Phase (matter)|phase]]

| 13.1 g/L, gas.

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| [[Solubility]] in [[Water (molecule)|water]]

| Hydrolyzes.

|-

<!-- | Other solvents e.g. [[ethanol]], [[acetone]] -->

<!-- | solubility info on other solvents -->

<!-- |- -->

| [[Melting point]]

| 2.3°C (275.45 K) <!-- (mention any decomposition) -->

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| [[Boiling point]]

| 17.1°C (290.25 K)

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! {{chembox header}} | Structure

|-

| [[Orbital hybridisation#Molecule shape|Molecular shape]] <!-- for simple covalent molecules (omit for most large molecules, ionics and complexes) -->

| Octahedral <!-- e.g. trigonal bipyramidal -->

|-

| [[Dipole#Molecular dipoles|Dipole moment]]

| 0 [[Debye|D]]

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! {{chembox header}} | Hazards <!-- Summary only- MSDS entry provides more complete information -->

|-

| [[Material safety data sheet|MSDS]]

| [[Tungsten(VI) fluoride (data page)#Material Safety Data Sheet|External MSDS]] <!-- please replace with proper link-->

|-

| Main [[Worker safety and health|hazard]]s

| Corrosive, highly toxic. <!-- e.g. highly toxic, explosive, flammable, corrosive -->

|-

| [[NFPA 704]]

| {{NFPA 704 | Health=4 | Reactivity=1 }}

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| [[Flash point]]

| Non-flammable.

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| [[Risk and Safety Statements|R/S statement]]

| [[List of R-phrases|R]]: ? <br /> [[List of S-phrases|S]]: ?

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| [[RTECS]] number

| ?

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! {{chembox header}} | [[Tungsten(VI) fluoride (data page)|Supplementary data page]]

|-

| [[Tungsten(VI) fluoride (data page)#Structure and properties|Structure and<br />properties]]

| [[Refractive index|''n'']], [[Dielectric constant|ε_r]], etc.

|-

| [[Tungsten(VI) fluoride (data page)#Thermodynamic properties|Thermodynamic<br />data]]

| Phase behaviour<br />Solid, liquid, gas

|-

| [[Tungsten(VI) fluoride (data page)#Spectral data|Spectral data]]

| [[UV/VIS spectroscopy|UV]], [[Infrared spectroscopy|IR]], [[nuclear magnetic resonance spectroscopy|NMR]], [[Mass spectrometry|MS]]

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! {{chembox header}} | Related compounds

|-

| Other [[Ion|anion]]s <!-- please omit if not applicable -->

| [[Tungsten(VI) chloride]],<br />[[Tungsten(VI) bromide]]

|-

| Other [[Ion|cation]]s <!-- please omit if not applicable -->

| [[Chromium(V) fluoride]],<br />[[Molybdenum(VI) fluoride]]

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| Related compounds

| [[Tungsten(IV) fluoride]],<br />[[Tungsten(V) fluoride]],<br /> [[Uranium hexafluoride]]

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| {{chembox header}} | <small>Except where noted otherwise, data are given for<br /> materials in their [[standard state|standard state (at 25°C, 100 kPa)]]<br />[[wikipedia:Chemical infobox|Infobox disclaimer and references]]</small>

|-

|}

'''Tungsten(VI) fluoride''', also known as '''tungsten hexafluoride''', is a colorless gas. It is nonflammable, but highly corrosive and very toxic.

In the accident, an interurban passenger train restarted after stopping at a red signal and shortly after collided with the rear of the [[Indian Pacific]] long distance passenger train waiting at a failed signal. A number of factors were involved, from equipment breakdown to poor phrasing of the rules. The most important factor was that the interurban picked up too much speed after restarting from the signal at stop, and was not able to see the rear of the long distance train around a sharply curved and deep cutting in order to stop in time to avoid a collision.

The molecule itself is octahedral with the symmetry point group of O_h.

The gas is most commonly used in the production of [[semiconductor]] [[circuits]] and [[circuit boards]], through the process of [[chemical vapor deposition]].<ref name="chemvap">Kirss, Rein U., Lamartine Meda. "Chemical Vapor Deposition of Tungsten Oxide." ''Applied Organometallic Chemistry'' 12 (1998): 155–160.</ref>

--[[User:208.189.200.2|208.189.200.2]] 00:28, 22 July 2007 (UTC)==Industrial Synthesis==

Seven people were killed in the accident. A [[Commission of Inquiry]] headed by [[Justice McInerny]] investigated the accident.

'''Tungsten hexafluoride''' of a purity high enough for [[semiconductor]] [[CVD]] is produced by the reaction of [[fluorine]] {| class="wikitable"

All seven people were in the front compartment of the first carriage of the interurban train. After the driver saw the oncoming train, he ran through the front compartment (the [[dead-man's control|dead-man's brake]] was automatically activated) and ran to the downstairs part of the carriage yelling "Get down!". Though the driver was badly injured he survived. As the driver ran through, a man from the front compartment ran upstairs to warn people there, and because of this he survived.

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|} [[tungsten]] metal. The metal is placed in a heated reactor, slightly pressurized to 1.2 to 2.0 psi, with a constant flow of WF₆ infused with a small amount of [[fluorine]] gas.<ref name="synth1">[http://www.patentstorm.us/patents/6544889.html Patent Storm]</ref>

== The train Reactions==

''Main article: [[DIM8020|DIM8067]]

WF₆(''g'') + H₂(''g'') + Al(''s'') → W(''s'') + HF(''g'') + AlF₃(''s'')

The train was a 4-car standard interurban [[V Set (train)|'V' Set]], labelled [[DIM8020|V21]].

This reaction occurs when [[tungsten]] is deposited on an [[aluminum]].

== Similar accidents ==

One application of this would be in the production of studs for semiconductor circuits.<ref name="use">[http://www.priorartdatabase.com/IPCOM/000038388/ Ip.com]</ref>

Other accidents involving "Stop and Proceed" include:

Tungsten can also be deposited on a [[silicon]] wafer or other semiconducting material via [[chemical vapor deposition]], or CVD, as follows:<ref name="react">[http://www.mne.umd.edu/grad/courses/old_courses_stuff_saved/659s_mats_&_proc_for_microelectronics/659s_spring_1998/enma659S_spr98_final_project_results/wcvd/sih4.html James Clark School of Engineering]</ref>

* [[Liverpool train disaster]]

* [[Regents Park train disaster]]

* [[Lindfield train disaster]]

WF₆(''g'') + W* → WF₆*

== See also ==

* [[List of disasters in Australia by death toll]]

2 SiH₄(''g'') + WF₆* → W(''s'') + 2 SiHF₃ (g) + 3 H₂(''g'')

The [[silane]] (SiH₄ reduces the tungsten from (VI) to its elemental state of zero.

{{Australia-rail-stub}}

[[category:1999 in Australia]]

==Safety==

[[Category:Australian railway accidents]]

On contact with water '''tungsten(VI) fluoride''' forms [[hydrofluoric acid]] (HF), which can penetrate the skin and cause damage to the subdermal tissues and bone. Inhalation burns the respiratory tract and can be toxic. WF₆ is a [[lachrymator]] which causes tearing and irritation of the eyes. Contact causes burns to the eyes, skin and mucous membranes.<ref name="msds">[https://www.mathesongas.com/msds/index.aspx Matheson Gas]</ref>

[[category:CityRail]]

In ''[[Uncle Tungsten: Memories of a Chemical Boyhood|Uncle Tungsten]]'', Oliver Sacks comments on how he wanted WF₆-filled balloons for his 65^th birthday, but the gas was too reactive. Had one of the balloons popped, the tungsten(VI) fluoride would have reacted with moisture in the air to form [[hydrogen fluoride]].

==References==

<div class="references-small"><references /></div>

==External links==

*[http://www.npi.gov.au/database/substance-info/profiles/44.html National Pollutant Inventory - Flouride and compounds fact sheet]

[[Category:Tungsten compounds]]

[[Category:Inorganic compounds]]

[[Category:Fluorides]]

[[Category:Metal halides]]

[[Category:lachrymatory agents]]

[[de:Wolframhexafluorid]]