Sort of a Fire question, but still public safety

[lightsandsirens5]

I think it has been said before, but this way of saying it helped me out.

Although they are slightly different, think of combustion as oxidation. (Actually it is, but through a different, rapid, exothermic reaction.) So, in our minds now: Combustion=Oxidation.

So we have the equation: (fuel) + O2 = By products...often H2O vapor in the case of Hydrogen containing substances (Most fuels) and CO2 in Carbon containing substances (Largely the class A type fires)

In the case of Hydrogen combustion we get:

2x H2+O2 = 2x H2O (Technically 2x H2+O2 <=> 2x H2O)

So we see that the rapid, complete oxidation of Hydrogen (catalyzed and driven by heat) results in the formation of water. Water is essentially a "by product" of the combustion (rapid, exothermic oxidation) of Hydrogen. Because Hydrogen is now already oxidized, it is no longer available to its environment, neither is the Oxygen that oxidized it. Of course the reaction will run in reverse, given the right conditions. But simply the heat and chemical chain reactions caused by, say a structure fire, are just not enough to drive the equation to the left.

 

[Veneficus]

I think it has been said before, but this way of saying it helped me out.

Although they are slightly different, think of combustion as oxidation. (Actually it is, but through a different, rapid, exothermic reaction.) So, in our minds now: Combustion=Oxidation.

So we have the equation: (fuel) + O2 = By products...often H2O vapor in the case of Hydrogen containing substances (Most fuels) and CO2 in Carbon containing substances (Largely the class A type fires)

In the case of Hydrogen combustion we get:

2x H2+O2 = 2x H2O (Technically 2x H2+O2 <=> 2x H2O)

So we see that the rapid, complete oxidation of Hydrogen (catalyzed and driven by heat) results in the formation of water. Water is essentially a "by product" of the combustion (rapid, exothermic oxidation) of Hydrogen. Because Hydrogen is now already oxidized, it is no longer available to its environment, neither is the Oxygen that oxidized it. Of course the reaction will run in reverse, given the right conditions. But simply the heat and chemical chain reactions caused by, say a structure fire, are just not enough to drive the equation to the left.

But the heat generated with flammable solids such as magnesium will drive the equation left, but as I eluded to earlier, water has specific properties that are different from most chemicals.

Generally there is a whole chapter on it in general chemistry, biochemistry, and molecular biology books.

The subject is too complex without that level of background understanding before discussion.

As a small example, the bond angle actually is unique to water and carries specific properties.

 

[lightsandsirens5]

Exactly, I thought I mentioned magnesium and other class D fires.

Guess not.

 

[Veneficus]

Exactly, I thought I mentioned magnesium and other class D fires.

Guess not.

sorry, looking back you did, but I completely missed it.

 

[Sandog]

Yes both intermolecular forces and molecular geometry play a big part in how molecules respond to external energy. At least several chapters if I recall.

If you care to be bored with the details.

http://itl.chem.ufl.edu/2045/lectures/lec_g.html
http://en.wikipedia.org/wiki/Molecular_geometry

 

[medic417]

Okay take it to a fire forum this is not ems related. I've got my eye on this. h34r:

 

[mycrofft]

but,but, what if someone were to accidentally eat sodium, or was shot with a sodium tipped arrow?

I know, call Mythbusters.


OK lightsandsirenssmartypants, what if you ignited beryllium in chlorine, huh? Then what? (You will nice no female conspirators are participating in this little excursion...)

 

[mycrofft]

NOTICE, not "nice". Darned Apple OS!

 

[Meursault]

There's worst things... my undergrad had a nuclear reactor.

Did you go to MIT? Or are there others lurking around the country?

Funny how MIT doesn't really play up the research reactor anymore. After all, BU's gotten such a good reception for their BSL-4 lab.

I'd take the low-power reactor over either of the other two, actually.

 

[JPINFV]

Did you go to MIT? Or are there others lurking around the country?

University of California, Irvine has one, and it seems that every 4-5 years the student newspaper runs a "Hey guys, bet you didn't know we have a reactor on campus" story.

http://chem.ps.uci.edu/~gemiller/reactor.html

 

[mycrofft]

A local former USAF base found traces of weapons grade uranium in the soil near the base dump about fifteen years after it was decommissioned (still very civilian active). What's with THAT?

Oh, the authoritative source about alkaline metals:
http://mythbustersresults.com/viewer-special-threequel

 

[Sandog]

Okay take it to a fire forum this is not ems related. I've got my eye on this. h34r:

Well... In a way, water chemistry does apply to EMS. :mellow: