It:arsine
Arsine
Arsine is a trihydride Arsenic (AsH3) compound that has uses in forensic science, synthesis of organoasenic compund and also as a semi conductor. While used in the detection of arsenic poisoning it is in itself a highly poisonous gas and must be handled with care
3-D structure of Arsine:
| It:arsine | |
|---|---|
| It:arsine | |
| General | |
| Systematic name | {{{Asenic trihydride}}} |
| Other names | {{{Arsine}}} |
| Molecular formula | {{{AsH3}}} |
| Molar mass | {{{77.97}}} |
| Appearance | {{{colourless gas}}} |
| Properties | |
| Density and phase | ? g/cm³, ? |
| Melting point | -62.4°C (210.75 K) |
| Boiling point | -116.3°C (156.85 K) |
| Structure | |
| Molecular shape | ? |
| Coordination geometry |
? |
| Crystal structure | ? |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | ? |
| NFPA 704 | |
| Flash point | ?°C |
| R/S statement | R: ? S: ? |
| RTECS number | ? |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Other anions | ? |
| Other cations | ? |
| Related ? | ? |
| Related compounds | ? |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
| Structure | |
|---|---|
| Molecular shape | {{{MolShape}}} |
| Coordination geometry |
{{{Coordination}}} |
| Crystal structure | {{{CrystalStruct}}} |
| Dipole moment | {{{Dipole}}} D |
Physical Properties
At standard room temperature Arsine is a colourless gas, denser than air. It is normally odourless but oxidises easily in the air giving it a vague garlic like odour. It is kinetically stable at room temperature though it decomposes at around 403.15K to its thermodynamically favoured base elements hydrogen and arsenic. This process can be sped up by increased humidity, light levels and the presence of a catalyst (such as aluminium).
Boiling Point = -62.4 oC
Melting Point = -116.3 oC
Density = 1.640 gcm3 (at -62.4 oc)
Bond Angle = 91.8°
Marsh Test
The Marsh test was a developed by one James Marsh as a means of detecting asenic poisoning. Body parts (typically the stomach) of a victim suspected of arsenic poisoning are reduced by zinc and sulphuric acid. If any arsenic is prsent then it is converted into gaseous Arsine that is fed through a heated tube. This will break down the arsine gas and form a black film of arsenic on the inside of the tube. This method was used during the 19th centuary and up to the middle of the 20th centuary, when it became replaced by more modern methods. The most common method of detection nowadays is neutron activation analysis.
Symptoms of exposure
Arsenic is posionous due to it's ability to bind with sulpher. It binds with sulpher in enzymes within the body (there are many enzymes containing sulpher) and it inhibits them from working. When tested on rabbits it was found that 2.5mg/kg of blood was a fatal dose.
While at concentrations of over 0.5 ppm a slight garlic odour is observed, much lower concentrations are still very harmful and are virtually undectable.
Upon initial exposure the victim will not suffer any symptoms for a period of up to 24 hours depending on the concentration. Then they will start to suffer symptoms including fever, chills, shivering, thirst, malaise, headache, confusion, shortness of breath, vomiting, diarhea, abdominal pain, red urine, weakness and cramping.
Poisoning may occur as the result of an inductrial accident. In parts of the world such as West Bengal and Bangladesh water supplies often become contaminated with arsenic, causing mass exposure to people living nearby.
Possible positive side effects
While generally very harmful there have been studies showing that trace amounts of arsenic may be an essential part of a balenced diet. These trace amounts can be found in most shell fish, such as prawns or oysters, and other fish such as plaice.
Roxarsone is a chemical that is given to farm animals to encourage growth. Animals that had arsenic completely removed from their diet have shown to have stunted growth linked to this change
References
[1]http://www.chm.bris.ac.uk/motm/arsine/arsineh.htm
[2] Johnson Warren C, American chemistry society journals 1937 Volume 59
[3] Yockel Scott, Journal of Chemical Physics 2005 V122(17) P174310/1-174310/14