AndersHoveland
Hazard to Other Members, due to repeated speculation and posting of untested highly dangerous procedures!
Posts: 1986
Registered: 2-3-2011
Member Is Offline
Mood: No Mood
|
|
Silicides reacting with water?
I read that magnesium silicide reacts with acid to form silane:
4 HCl + Mg2Si → SiH4 + 2 MgCl2
While sodium silicide reacts with water to form hydrogen:
2 NaSi + 5 H2O → 5 H2 + Na2Si2O5
Why the difference? Are traces of hydrogen produced from the reaction of Mg2Si with hydrochloric acid? Is some silane released when sodium silicide
reacts with water?
Silicon nano-powder can also react with water at a temperature of only 70-90 °C, releasing hydrogen, even though bulk silicon is essentially
unreactive towards water.
(John Foord at Oxford University)
|
|
|
Mixell
Hazard to Others
Posts: 449
Registered: 27-12-2010
Member Is Offline
Mood: No Mood
|
|
Well, SiO2 and silicates are very favorable products. But for them to occur there needs to be a source of oxygen (like water) and something to grab
what ever the oxygen is attached to (or a reducing agent that eliminates the hydrogen as H2). But silicates don't tend to form in an acidic medium,
and usually precipitate as silicic acid (which readily looses water molecules and turns into a polymeric form of SiO2, silica gel) when pH=~0.
Silane does react slowly with water, turning into silicic acid.
Traces of hydrogen are most likely produced.
|
|
|
AndersHoveland
Hazard to Other Members, due to repeated speculation and posting of untested highly dangerous procedures!
Posts: 1986
Registered: 2-3-2011
Member Is Offline
Mood: No Mood
|
|
well, silane does hydrolyze in alkaline aqueous solution:
http://www.tandfonline.com/doi/abs/10.1080/00986448708960479...
"REMOVAL OF SILANE GAS BY ABSORPTION INTO ALKALINE SOLUTIONS: ALKALINE HYDROLYSIS OF SILANE", E. Sada, H. Kumazawa, S. Hattori
|
|
|
12AX7
Post Harlot
Posts: 4803
Registered: 8-3-2005
Location: oscillating
Member Is Offline
Mood: informative
|
|
Elemental Si is oxidized by O2 and H2O. "Nano-powder" basically means "pyrophoric silicon", it behaves much the same way as other pyrophoric powders.
Tim
|
|
|
vmelkon
National Hazard
Posts: 669
Registered: 25-11-2011
Location: Canada
Member Is Offline
Mood: autoerotic asphyxiation
|
|
Quote: Originally posted by AndersHoveland  | I read that magnesium silicide reacts with acid to form silane:
4 HCl + Mg2Si → SiH4 + 2 MgCl2
While sodium silicide reacts with water to form hydrogen:
2 NaSi + 5 H2O → 5 H2 + Na2Si2O5
Why the difference? Are traces of hydrogen produced from the reaction of Mg2Si with hydrochloric acid? Is some silane released when sodium silicide
reacts with water?
Silicon nano-powder can also react with water at a temperature of only 70-90 °C, releasing hydrogen, even though bulk silicon is essentially
unreactive towards water.
(John Foord at Oxford University)
|
Your question is confusing.
The question should actually be, "Does Mg2Si react with water?"
The answer, I guess, is no.
Then the question should be "Why?".
Because NaSi reacts with water and that's what your want to compare with.
As for hydrochloric acid, perhaps NaSi also reacts and produces some SiH4. Some of the NaSi probably would react with the water.
I don't know the actual answers, I'm just trying to clarify.
|
|
|
![[*]](images/xpblue/default_icon.gif){kind=icon}
