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Exothermic reactions that release hydrogen?

  1. Jul 31, 2007 #1
    Hello, I was wondering if there are any exothermic (or otherwise spontaneous) chemical reactions that release hydrogen, in which the reagents and products aren't strongly hazardous?

    I know of the reaction of alkali metals with water, but these produce strong alkaline solutions.. Perhaps one could use some extra additive to make this less hazardous (e.g. maybe precipitate some harmless salt of the alkali metal)?
     
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  3. Jul 31, 2007 #2

    chemisttree

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    Any reagent that is reactive enough to release hydrogen exothermically will by definition be hazardous. Hydrazine is a perfect example of this.

    H2N2H2 + catalyst (Ru, Fe2O3, FeN...) -----> 2H2 + N2 + heat
     
  4. Jul 31, 2007 #3

    mrjeffy321

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    Just two, exothermic, Hydrogen producing chemical reactions that I can think of off the top of my head would be reactions between metals and acids (for example, Magnesium reacting with Hydrochloric acid), and also the reaction between Aluminum metal and a Sodium Hydroxide solution.
     
  5. Dec 11, 2007 #4
    Easy method to extract hydrogen from water discovered

    Saw this on Eco-Talk TV show and researched it. It's pretty interesting.

    Apparently, if you melt together aluminum and gallium and create an alloy, when you later add water, it reacts and releases hydrogen. This was discovered a few months ago at Purdue U., patented and the rights have been sold to a company named AlGalCo, LLC.

    Read more here:

    http://www.physorg.com/news98556080.html

    The remaining question is whether other, less expensive metal alloys would exhibit similar properties.

    Reminds me of all those turn-of-the-century anectodotal stories about inventors making fuel from water, who were put out of business by the oil companies. Maybe some of them were true.
     
  6. Dec 11, 2007 #5
    Alcali metals, for example (Gallium is quite expensive). Anyway, if it weren't for its higher toxicity, you could use mercury, which has the same effect on aluminum; worse, if you touch an aluminum body with an object having some mercury metal or mercury(II) salt, that Al body will start to "rotten" in air, especially in the presence of acqueous vapour. (Hg amalgamates continuously with Al making it react with oxygen or water).
     
  7. Dec 11, 2007 #6

    chemisttree

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    I believe that high lithium content aluminum alloys will do the same thing. The energy output (H2) per weight is much better for this alloy than the Al/Ga as well. It certainly costs less as well.

    All this is moot, however, since any metal that can produce hydrogen in contact with water will never be available to the public. This is due to the use of these metals in the illicit manufacture of drugs (and you know who you are!).

    As soon as this material was made available to the market it would go to baaad places and people.

    What's next? A hemp-powered steam car? Maybe for the California market. I could just imagine it now.... "Oh, man! I need this medical marijuana to power my car to go to the doctor!" Yeah, and I need to tailgate him as well! (for medical reasons, of course)
     
  8. Dec 11, 2007 #7
    thanks for your reply - it is interesting and insightful, but your comments on hemp are so far off base that, with all due respect, I wonder if you have ever researched anything on this topic. If you were to do so, you would learn that the industrial version of hemp has many, many wonderful properties and uses; produces a great deal of natural oils, could be used to supplant our dependency on foreign oil, and most important of all - contains about 0.03% THC. That is, you could not get high on it if you tried.

    Unfortunately, the 'reefer madness' era and the Reagan era has all but shut down most industrial uses of hemp, unless you live in Canada.

    But, I am not trying to start another thread, here, just pointing out some important facts.
     
  9. Dec 11, 2007 #8

    chemisttree

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    I was kind of hoping that my hemp comments were a little off somewhere...
    I didn't know about the hemp oil, though. Thanks for the heads up.
    (now, where did that tongue-in-cheek emoticon go?)
     
  10. Dec 20, 2007 #9
    Mg + H20

    If the water is steam, it'll work quicker, but the Mg will replace the H2 in a single displacement reaction giving you hydrogen gas.
     
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