Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Unusual Salt-Water Reaction?

  1. May 29, 2007 #1
    http://www.wpbf.com/news/13383827/detail.html

    The gist is like this: radiowaves are used to heat up saltwater, making it up to 3000F. Speculation exists over the energy usefulness of this.

    Whats the opinion here on it? I'm no chemist, so its all enxothermic to me.
     
  2. jcsd
  3. May 29, 2007 #2

    Garth

    User Avatar
    Science Advisor
    Gold Member

    Interesting.

    I notice the power rating on the RF system goes up to the 1.4 KW mark.

    First. I would dispute strongly that he is obtaining more heat power out than he is putting RF power into the experiment. (If he is then this must be another form of 'cold fusion'!)

    Second. There are radio stations of much greater power that transmit over the sea. (While in the Navy in the Seychelles I saw the FEBA Christian missionary radio transmitter that had a series of transmitting aerials actually sitting in shallow water transmitting to Asia. The sea didn't catch fire!)

    Garth
     
  4. May 29, 2007 #3

    russ_watters

    User Avatar

    Staff: Mentor

    It takes more energy to split water into hydrogen and oxygen than you get back by burning it, no matter how you do it.
     
  5. May 29, 2007 #4

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Yep, no such thing as free energy. He may have gotten interesting results suggesting something that we don't fully understand [or maybe not] but a careful accounting of the energy input will certainly show a net loss. I suspect that if the basic story is true, the effect is what interests engineers and not the idea of free energy.
     
    Last edited: May 29, 2007
  6. May 30, 2007 #5

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I've decided to open this thread again but not to discuss free energy. Any such posts will be deleted. If there is any more information on the effect reported [and from better sources], please post it.
     
  7. May 31, 2007 #6
    It's remarkable in any event because I've never heard of dissociating water into it's constituent elements by radio waves. I've only heard of this done by electrolysis or extreme heat.

    The question I have is why are they focusing on salt water? Does fresh water work? If not, why?
     
  8. May 31, 2007 #7

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    I noticed that the flame is the signature yellow of sodium (I didn't have my spectrometer out, so I'm not sure about that). Is it possible that the sodium of salt water is releasing energy in the process? I've only just seen this, so feel free to shoot it down, and no insults are necessary, I'm teaching my class and a student is watching.
     
  9. May 31, 2007 #8
    The bond enthalpy of NaCl (412.1 KJ/mol) is farely high, almost half of the strongest diatomic bond enthalpy CO (1076.5 KJ/mol). But at such a high temperature this wouldn't be a problem. If the Sodium was giving of energy, wouldn't you have chlorine gas released?
     
  10. May 31, 2007 #9
    IIRC there are seven salts in sea water. There are more variables to consider here than just H20 and NaCl. After common sodium chloride I believe epsom salt is the next most prevalent. There's enough of it that it's viable to extract magnesium from salt water without it being too complex or costly.
     
  11. May 31, 2007 #10

    mrjeffy321

    User Avatar
    Science Advisor

    It is an interesting demonstration he puts on.

    It is not unreasonable to assume that the Yellow flame color is due to the Sodium ions present in the water. The Sodium [Chloride] does not really have to react itself to give impart the yellow color to the flame; you could just stick some salt into an ordinary flame (example, a non-luminous butane lighter’s flame) and turn the flame yellow, then you could pull out the colorant and it should still be NaCl and the flame color will return to normal.
    The yellow color Sodium ions impart in flames will easily over power other colors due to other salts present.

    Could it be that he is, very, locally heating the water up to a temperature so high that the decomposition reaction becomes spontaneous (2 H2O --> 2 H2 + O2) and then the H2 and O2 bubbles float away and get burnt. In the process of bubbling up, small droplets of NaCl solution get thrown up into the air and the water soon evaporates leaving small NaCl particles in the flame which act to give it the distinctive yellow color.
    But if water is really decomposing and both H2 and O2 are produced, the I would have expected the combusting gasses on top of the test tube to behave much more explosively. If you ignite a mixture of H2 and O2 gas in the proper proportion, it explodes quite quickly with a load pop, it does not burn slowly like a candle wick,
     
  12. May 31, 2007 #11

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    But in this process there is a continuous generation of O and H, not a large buildup, so it appears to be breaking down and then combusting at the same rate.

    I'm afraid I'm gonna say HOOEY!

    Maybe it's a more efficient manner of getting H2 though?
     
  13. Jun 1, 2007 #12

    russ_watters

    User Avatar

    Staff: Mentor

    Well, it is certainly going to combust at the same rate it breaks down at - it couldn't combust at any other rate!
    I doubt it - radio waves (or whatever he's using) are hard to contain and focus so that you don't lose a lot of it. I missed where Garth saw the 1.4kW, but a flame like that can't be producing more than a couple hundred watts.
     
    Last edited: Jun 1, 2007
  14. Jun 1, 2007 #13

    NoTime

    User Avatar
    Science Advisor
    Homework Helper

    There was an implication, from the cancer cure part of this, that metal nanoparticals are also included in the water.
     
  15. Jun 2, 2007 #14

    Chi Meson

    User Avatar
    Science Advisor
    Homework Helper

    Well sure, my point was that this is why it doesn't characteristically "pop."
    Yeah, it sounds more like hooey the more I think about it. I was willing to consider it for a while, though. It's an interesting demo, an interesting phenomenon; but really, the guy thinks it's going to power a car?

    This news story dates back to February, and there has been not much residual chatter afterward about it. I guess the guy has been talked to by now.
     
    Last edited: Jun 2, 2007
  16. Jun 2, 2007 #15

    mrjeffy321

    User Avatar
    Science Advisor

    Whether it is a practical way of powering a car or not, that is usually a good way to get attention for yourself...call the news companies up and say you found a way to power an automobile using "water" and they will send a camera crew right over.
     
  17. Jun 2, 2007 #16

    russ_watters

    User Avatar

    Staff: Mentor

    Because it isn't being collected and concentrated before being ignited. If the flame isn't there, it just comes out of the test tube and dissipates into the air. I've only done electrolysis once, in high school, but the test tube was inverted over a beaker of water and we collected it for a minute or two before igniting it.
    It was on a local news station's website here last week. Roughly the same story: http://www.nbc10.com/irresistible/13405989/detail.html
     
  18. Jun 2, 2007 #17

    mrjeffy321

    User Avatar
    Science Advisor

    I do electrolysis all the time.

    In my experience, if you have a stream of Hydrogen gas bubbling up from a pool of water and you hold some type of ignition source (like an open flame) over the area where the H2 gas emerges, you will hear a series of small pops as the H2 mixed with the O2 in the air and ignites. In order to hear the pops, though, you usually need to have decently sized H2 bubbles, otherwise nothing really happens.
    So I guess the H2 bubbles coming out of this guy's water a very tiny and the production rate is slow and continuous.
     
  19. Jun 2, 2007 #18
    If you placed a bath of salt water in contact with a bath of distilled water, the chemical potential gradient would cause the salt to diffuse and establish stable equillibrium. Essentially, what you would have is a weak battery. In theory, it would be possible to extract work from this transport process. In practice, the amount of work extracted would be too small to care about.
     
  20. Jun 2, 2007 #19
    Wouldn't this be Gibbs Free Energy?:confused:
     
  21. Jun 2, 2007 #20
    Yes, Gibbs Free Energy is correct.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Unusual Salt-Water Reaction?
  1. Unusual videos (Replies: 26)

  2. Unusual Questions (Replies: 73)

  3. Would it be unusual (Replies: 7)

Loading...