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  • Flaming Water?

    For reasons related to my unrelenting facination with Deep Wizardry, I'm taking an oceanography class at my university at the moment. We've covered deep sea vents-white smokers, black smokers, etc etc- as well as underwater volcanic activity, but I haven't seen any mention of water being able to do what it does during the Lone One's apperance as a lava snake.

    The water that came into contact with it-unable to boil at these pressures, regardless of the heat applied to it- did the impossible, the only thing it could do: it burst into flame. Small tongues of blue-violet danced and snaked along the outward-reaching tentacles of the lava.
    Mostly out of idle curiousity, I'm wondering, can that actually occur? Water on fire?
    it's so easy to laugh at yourself when all those jokes have already been written...
    who're you fooling if the fools are right?

  • #2
    Tricky one... the only similar thing I can think of is with metal fires (i.e. burning metal), when adding water can make things worse. The reason is that at sufficiently high temperatures, the water ends up catlysing the oxidation process. (Exactly how high depends on the metal, but generally, if a mteal is burning in the first place, it reasonable to assume that it is sufficiently hot).

    Lava is primarily molten basalt, which is mostly silica (SiO2). The reaction between water and silica ( 2[H20] + SiO2 -> 02 + SiH4 ) didn't strike me as being exothermic. There is a slight problem with determining this for certain. The main tool one uses to determine this is to comparing the enthaply of formation of each side, but all the data I have found is either for room temperature or absolute zero - and always at atmospheirc pressure.
    What I will try and do is find how the numbers change with increasing temp/pressure, and try and see if for sufficently (that word again) high temp/pressure, the reaction could be exothermic.

    If that's the case, then yes, you would get "burning" water on contact with lava at the bottom of the sea.


    Data which would be useful:
    - temperature of molton lava
    - pressure at bottom of the ocean
    - enthalpy of formtaion of water (H20), Silica (SiO2) and Silane (SiH4) at this temp/pressure. Failing that, how any of themn change as a fucntion of temp/pressure. (Even if it's just "goes up" or "goes down"). (That of oxygen (O2) is zero by definition)

    (Who'd've thought A-level chemistry would be so useful?)
    "Never let your sense of morals prevent you from doing what is right" - Salvor Hadrin, in Isaac Asimov's Foundation

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    • #3
      I think I remember reading or seeing somewhere that when they weld under water thats happens! But it still bubbles!! I mean a welding torch would been very hign temps! But taking into account the depth in DW I don't know. Sorry
      Fox
      God its hard to keep up with everything here!!

      Memember of The STTF (Save the topic foundation).

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      • #4
        An underwater welding torch is different. It just blows out a large "cacoon" of air continuously, so that the water cannot get to the welding itself.
        "Never let your sense of morals prevent you from doing what is right" - Salvor Hadrin, in Isaac Asimov's Foundation

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        • #5
          oh, I knew that! I did.................. No I did'ant I cant lie!! I'm so dumb!!! Sorry everyone
          Fox
          God its hard to keep up with everything here!!

          Memember of The STTF (Save the topic foundation).

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          • #6
            Oh my god Wilf...I'm taking my 'A' levels this year but I would never have thought of what you said. But then I suck at chemistry.

            Let me try to explain the 'flaming water' phenomenon from a physical perspective(as opposed to chemical;I think I'm better at physics):

            When water boils, part of the heat energy supplied is used in breaking the inter-molecular forces of attraction, part of it is used in overcoming surrounding pressure(the liquid-to-gas transition involves an increase in volume of the water, thus the boiling water does work in 'pushing' outwards against surrounding pressure). However, at the depths at which the action in Deep takes place, the hydrostatic pressure of the water is so large that water cannot expand into gas and hence it is impossible for water to boil; but the heat from the lava-snake has to go somewhere, so the water ends up undergoing combustion, and hence the occurrence of flames. Maybe Wilf the Chemistry Expert could supply the equation for this reaction? I have no idea how oxygen would react with water...maybe form hydrogen peroxide? :P
            you'll never be an artichoke;even vegetables have a heart

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            • #7
              thats cool i dont have chemistry this year but you really can have a fire in water if there is oil on the water or somthing like that then htere can be a fire on water
              Dai stiho cousins
              ~~~Ezra

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              • #8
                Originally posted by wizardsrreal:
                thats cool i dont have chemistry this year but you really can have a fire in water if there is oil on the water or somthing like that then there can be a fire on water
                Dai stiho cousins
                ~~~Ezra

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                • #9
                  sry about the double post dudes
                  Dai stiho cousins
                  ~~~Ezra

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                  • #10
                    Ahh, you didn't have to make it a third in a row...

                    No, it's okay, just be warned that you're not allowed to double (or triple ) post all in a row in one topic. Also, try to avoid one liners; they cost DD more money without getting anything done. You can edit posts by clicking the eraser button at the top of your post.
                    Gigo: Hey, it's the person who puts 'asian' in 'caucasian'. Hi, Gryph. | | | wildflower: Hmm... should I side with "Gryph is more insane" based on conclusive evidence, or "Sharky is more insane" based on tradition? | | | [url="http://mariposa-mentiro

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                    • #11
                      ahhh chemistry, but i will attempt this

                      What if the molecule (H2O) was heated up enough that it split into its components? then we would end up with H2(gas) and O2(gas), one of which is combustible and the other fuels fires. It might burn then... But I dunno if enough heat could be supplied to do that. It would require a heck of a lot of energy to ionise the water completely, and then even more to form the gasses.

                      poss reaction:
                      2H2O + energy ----> 2H2 +O2 -----> 2H2O +energy

                      hmmmn... forms back to water...

                      or taken from what cheshire said earlier, perhaps after it has ionized, and with all the heat that is around, it will react with the water as well... but it would still form H2O as the end product...

                      Anyone care to comment or correct?

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                      • #12
                        Originally posted by cheshire:
                        Oh my god Wilf...I'm taking my 'A' levels this year but I would _never_ have thought of what you said. But then I suck at chemistry.
                        ...
                        Maybe Wilf the Chemistry Expert could supply the equation for this reaction? I have no idea how oxygen would react with water...maybe form hydrogen peroxide? :P
                        Well, if you are taking your A-levels this year, then you still haven't been taught t large chunk of the course. Also, I am not a chemistry expert... I've just done more chemistry then the avarege person.
                        Yes, you can react water with oxygen, but more importantly, where would the oxygen come from? Going back to my intial reaction betwene silica (lava) and water:
                        2[H20](l) + SiO2(s) -> 02(g) + SiH4(g)

                        Some data:
                        - Atlantic ocean has average depth of 12,000ft (3,600m) and the greatest depth is 28,374ft (8,648m) in the Puerto Rico Trench. For sake of argument, I'm gong to take the relevent depth to be 5,000m.
                        - Pressure underwater is 1atm per 10m depth. This means the relevent pressure is 500atm (500 times atmospeheric pressure, (roughly 7,300 lbs/sq inch [psi] or 15,000 inHg), which is pretty darn huge.
                        - According to a handy calculator I found, the boiling point of water at this pressure is 600C (1,100F).
                        - The temperure of lava depends hugely on its composition. Undersea lava tends to basaltic (as is Hawaiian lava), and thus has a melting point of around 1000-1250C (1800-2300F)
                        - this is well above the bp of water at the temperstures given above. Even at the bottom of the Puerto Rico Trench, the bp of water is 'only' 713C (1,315F).
                        - HOWEVER... there is the point cheshire rasied. Sure, the water could boil, but the steam would have to occupy the same space as the water it boiled from. So, we would have steam at over 600C (1,100F) and 500atm (7,300 psi).

                        So, the reaction above shoudl actually read:
                        2[H20](g) + SiO2(s) -> 02(g) + SiH4(g)
                        This, we have two moles of gas on each side, meaning whether or not the reaction will 'go' doesn't depend on pressure, only temperature. Therefore, all I need is the enthalpy of formation of steam (H20), Silica (SiO2) and Silane (SiH4) at this temperture, or failing that, whether they go up or down as tempersure increases.

                        I have to go now, else I would find out and post right here... tune in later!
                        "Never let your sense of morals prevent you from doing what is right" - Salvor Hadrin, in Isaac Asimov's Foundation

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                        • #13
                          Originally posted by Wilf:

                          Yes, you can react water with oxygen, but more importantly, where would the oxygen come from? Going back to my intial reaction betwene silica (lava) and water:
                          2[H20](l) + SiO2(s) -> 02(g) + SiH4(g)
                          Well I suppose even deep sea creatures need to breathe oxygen to stay alive? So there should already be oxygen present in the sea water. And if it's enough to sustain marine life, the concentration should be sufficient for combustion to occur? So we don't really need water and silica to react to produce oxygen.
                          you'll never be an artichoke;even vegetables have a heart

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                          • #14
                            Originally posted by cheshire:
                            Originally posted by Wilf:

                            Yes, you can react water with oxygen, but more importantly, where would the oxygen come from? Going back to my intial reaction betwene silica (lava) and water:
                            2[H20](l) + SiO2(s) -> 02(g) + SiH4(g)
                            Well I suppose even deep sea creatures need to breathe oxygen to stay alive? So there should already be oxygen present in the sea water. And if it's enough to sustain marine life, the concentration should be sufficient for combustion to occur? So we don't really need water and silica to react to produce oxygen.
                            Yes, you're absolutly right... there is a fair amount of oxugen dissolved in the water. However, we were trying to see if it was possible for the water to "burn", which could not take place by reaction with oxygen alone.

                            [N.B. The silica is being reduced by the water, which is equilant to the water being oxidised by the silica. So, in this sense, the water is "burning".]
                            "Never let your sense of morals prevent you from doing what is right" - Salvor Hadrin, in Isaac Asimov's Foundation

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                            • #15
                              Oooh! Ooh! Remember? The whales (who normally have to surface to breathe) brought extra breathing air down with them for the Song. This was important to the plot-- they were afraid that the battles and delays would make them run out of air.
                              (I'm so glad you started this topic-- I always wondered if the science held for this scene.)

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