Sort of a Fire question, but still public safety

[Devilz311]

How can water keep the fire from getting oxygen, when Oxygen is sorta one of the main ingredients in water?

If you think along those lines, we should be able to breathe underwater... You can't just separate liquid molecules like that.

 

[lightsandsirens5]

If you think along those lines, we should be able to breathe underwater... You can't just separate liquid molecules like that.

He does have a valid point.......

 

[lightsandsirens5]

I must add, that there ARE cases where water exacerbates combustion. Ie. In the case of a fire involving pure magnesium.

 

[Devilz311]

I must add, that there ARE cases where water exacerbates combustion. Ie. In the case of a fire involving pure magnesium.

Or a kitchen grease fire, or electrical fire...

 

[lightsandsirens5]

Or a kitchen grease fire, or electrical fire...

Well, in the case of the grease fire, the water simply spreads the fuel around, exposing more surface area.

Water on an electrical fire is bad simply because impure water will conduct electricity, right back to YOU!

 

[Meursault]

I must add, that there ARE cases where water exacerbates combustion. Ie. In the case of a fire involving pure magnesium.

I've seen warnings* about metals, including Mg, that aren't all that reactive at room temp but burn sufficiently hot to split water, resulting in little cooling and a hydrogen fire. Fun.

The lesson to take away here is that if you see fire in a machine shop or chem building, just run far away before fire apparatus shows up.

There's at least one building near me that machines a lot of beryllium, and has a duct system to suction up all the fines. That's a nightmare waiting to happen. Burning clouds of toxic dust!

*Ignore the hysteria about GASOLINE!!111.

 

[medicdan]

Our biggest public health danger today is a compound called DHMO, responsible for millions of deaths a year worldwide.
Learn more:
http://dhmo.org/

 

[akflightmedic]

Our biggest public health danger today is a compound called DHMO, responsible for millions of deaths a year worldwide.
Learn more:
http://dhmo.org/

Oh NO! NOT dihydrogen monoxide.....oh, how deadly....

I used to send out a chain email to my family and friends to see who takes the bait and jumps on the wagon...

 

[Handsome Robb]

Wouldn't dihydrogen monoxide be water?? :wacko:

It's early pardon me if I ruined your joke

 

[74restore]

It is all due to VALENCE ELECTRONS... they are the outermost electrons in the atoms of these individual elements, and are responsible for their REACTIVITY.

Hydrogen on the periodic table is in group 1A so it has just 1 valence electron. Oxygen is in 6A so it has 6 valence electrons. In order for a molecule/compound to become stable, it must have EIGHT VALENCE ELECTRONS (just like the noble gases Neon, Argon, etc). So:

hydrogen: 1
Oxygen: 6

= 7.... so there must be one more electron... theres where the "2" comes in H2O.

hydrogen: 2
oxygen :6

= 8 electrons which makes a STABLE molecule.

You are right in saying that the component parts alone (pure O2 and H2) are very unstable and combustable, but when they are combined and SHARE valence electrons to make EIGHT, not only does a new substance form (water) but it is completely stable.

Also, it takes a TREMENDOUS amount of energy to break apart these elements again, which is why it is so useful in fighting fires

Let me know if this doesnt make sense...

 

[tylerp1]

water is a very, very special molecule..good links by previous posters..

speaking of alkaline metals, here's a sweet vid showing how they react with water!

http://www.youtube.com/watch?v=QROSCx4fYFc

 

[silver]

Can you explain it? I mean in different words, the second part seems analogous to defining a word with the word. you cant because you cant?

[youtube]6dTvSa1rCOY[/youtube]

 

[Shishkabob]

you do realize that's not helpful, and has already been stated several times?

MMIZ recently made an entire thread about not posting when you have nothing worthwhile to say.

Maybe you need to re-read what I said. It all has to do with electrons. It's plenty helpful, you just didn't understand it, hence why you posted this thread in the first place.

 

[mycrofft]

Burning metals use water but it doesn't burn.
You can burn water once you have electrolyzed it. That yields water and heat.
Gasoline, since it absorbs so much heat so efficiently, then generates gasses like CO2 which will stifle most combustion, would seem the perfect firefighting agent.

EDIT: here's the sodium plus water equation
2Na(s) + 2H2O(l) ----> 2NaOH(aq) + H2(g)
Those two hydrogens are being released in the presence of very high temperature flame and an oxygen atmosphere. GOing to make more water and more heat.

 

[STXmedic]

Wouldn't dihydrogen monoxide be water?? :wacko:

It's early pardon me if I ruined your joke

Good job, Rob.

*hands cookie and pats head*

:rofl:

 

[Hate]

It is all due to VALENCE ELECTRONS... they are the outermost electrons in the atoms of these individual elements, and are responsible for their REACTIVITY.

Hydrogen on the periodic table is in group 1A so it has just 1 valence electron. Oxygen is in 6A so it has 6 valence electrons. In order for a molecule/compound to become stable, it must have EIGHT VALENCE ELECTRONS (just like the noble gases Neon, Argon, etc). So:

hydrogen: 1
Oxygen: 6

= 7.... so there must be one more electron... theres where the "2" comes in H2O.

hydrogen: 2
oxygen :6

= 8 electrons which makes a STABLE molecule.

You are right in saying that the component parts alone (pure O2 and H2) are very unstable and combustable, but when they are combined and SHARE valence electrons to make EIGHT, not only does a new substance form (water) but it is completely stable.

Also, it takes a TREMENDOUS amount of energy to break apart these elements again, which is why it is so useful in fighting fires

Let me know if this doesnt make sense...

So you are saying that having 8 valence electrons on each atom in a molecule makes that molecule stable?

What about TNT? Every atom in TNT has an octet, but it is far from completely stable. What about Hydrochloric acid? Both the hydrogen and the chlorine are each surrounded by 8 electrons, but HCL is still a very strong acid.

You also say that both O2 and H2 are both very unstable, but both of these molecules have an octet as well, or in the case of H2 a full outer shell.

 

[Hate]

Maybe you need to re-read what I said. It all has to do with electrons. It's plenty helpful, you just didn't understand it, hence why you posted this thread in the first place.

I didn't want to waste thread space, so I will reference the above post.

Can you explain to me how it has to do with the electrons?

 

[Hate]

If you think along those lines, we should be able to breathe underwater... You can't just separate liquid molecules like that.

Liquid molecules are easy to separate.

Can you separate water and oil?

 

[lightsandsirens5]

Liquid molecules are easy to separate.

Can you separate water and oil?

Uhhhh...not sure that applies.

 

[JPINFV]

There's at least one building near me that machines a lot of beryllium, and has a duct system to suction up all the fines. That's a nightmare waiting to happen. Burning clouds of toxic dust!

*Ignore the hysteria about GASOLINE!!111.

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