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Is it possible to split water with sound wave?

  1. Nov 18, 2012 #1
    I have been researching about splitting water including electrolysis, but I came across about using ultrasonic sound wave to split water, I search around and it said that water will decompose at 42000 hertz, is this true, because I am going to do it for my project. May anyone please give me a link and theory behind it because I couldn't find it. Thank you.
  2. jcsd
  3. Nov 18, 2012 #2


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    Cavitation in physics is the formation of vapor bubbles of a liquid in a region where the pressure of the liquid falls below its vapor pressure. The extreme pressure reduction literally “rips” the water molecules apart and creates a bubble. This bubble contains gas that had been dissolved in the liquid. Cavitation bubbles can easily be seen near the tips of a rapidly spinning propeller under water. For a good description of hydrodynamic cavitation, see: http://en.wikipedia.org/wiki/Cavitation

    Cavitation in liquids may also be caused when the low pressure portion of a powerful acoustic (sound) wave "rips" the water molecules apart and causes bubbles to form. There is no specific frequency that causes cavitation; a wide range from very low frequencies through ultrasonic frequencies all will cause cavitation in water. When a cavitation bubble collapses it compresses the gas and vapor inside it to an extremely high temperature. This can be used to cause chemical reactions not possible without acoustic cavitation. Under some specific conditions the process will emit visible light called “sonoluminescence”.

    An excellent technical paper authored by some of the original pioneers in the field is this:
    “Acoustic cavitation and its chemical consequences”
    By Kenneth S. Suslick, et al.

    See these images for acoustic cavitation:

    Suggested search terms you may use in Google searches to learn more:

    hydrodynamic cavitation
    physics of acoustic cavitation in liquids
    acoustic cavitation ultrasound

    Just as a side note, in high power sonar systems there is always the possibility of trying to transmit so much acoustic power that cavitation occurs at the face of the output transmitter (projector). This bubble field will damage the projector quickly and must be avoided. Worse yet, the bubble field drastically changes the acoustic impedance of that water and so the output sound field is attenuated. This is highly undesirable as well. As a result, sonar engineers always avoid allowing cavitation to occur.

  4. Nov 18, 2012 #3


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  5. Nov 18, 2012 #4
    thank you so much
  6. Nov 18, 2012 #5


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    Thank you, NascentOxygen, for addressing the kevin tee's question.

    My lesson learned: pay closer attention to what the OP is asking.

  7. Nov 19, 2012 #6
    Can hydrogen and oxygen be harvest and used? I found out that that the temperature of cavitation is more than 5000 kelvin, so will hydrogen and oxygen be combust before it can be used?
  8. Nov 19, 2012 #7


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    kevin tee, OOPS! Excuse me, please. I mistakenly posted all that information about cavitation without understanding your question. While it is true that acoustic cavitation bubbles, when collapsing, can generate temperatures above 5,000 degrees Kelvin, this process alone does not “split” water into Hydrogen and Oxygen.

    May I suggest you begin by reading and studying this Wikipedia article?
    Here you will discover many various ways to split water. Please use the references at the bottom.

    Here find an article about using ultrasound to generate free radicals from sonolysis of water: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3171683/

    Here is an article called “Direct Water Splitting Through Vibrating Piezoelectric
    Microfibers in Water”.
    "ABSTRACT We propose a mechanism, a piezoelectrochemical effect for the
    direct conversion of mechanical energy to chemical energy. This phenomenon is
    further applied for generating hydrogen and oxygen via direct water decomposition
    by means of as-synthesized piezoelectric ZnO microfibers and BaTiO3 microdendrites."
    http://www.geology.wisc.edu/.../Hong_et_al_2010_J_Phys_Chem_Lett.pdf [Broken]

    Here is a paper called “Sonophotocatalytic decomposition of water using TiO2 photocatalyst”. “In the present work, simultaneous irradiation of ultrasound and light in order to decompose water to hydrogen and oxygen continuously has been attempted. This attempt, if proved successful, will be a typical example for a hybrid effect.”

    kevin tee, I encourage you to continue searching for new, energy efficient, and innovative ways to decompose water. Your research, if successful, has the potential to revolutionize our entire production of energy.

    Cheers and good luck,
    Last edited by a moderator: May 6, 2017
  9. Nov 20, 2012 #8


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    Either way you can't run a car on pure water :-)
  10. Jun 25, 2013 #9
    I am new here and i find it interesting and curious at the same time.. myself I am a technician and innovator as well over the years of looking into HHO i haven't yet seen one claim of water in liquid form as combustible , however in the gas form it is certainly, there are numbers of vehicles that run on natural gas, propane even hydrogen.
  11. Jun 26, 2013 #10


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    james1967, Welcome to Physics Forums!

    Do not be misled by post #8 by CWatters! This thread was originated by kevin_tee asking about how to "split" water using acoustic energy. He never said why he wanted to do that, but clearly having the Hydrogen gas and the Oxygen gas could be useful for generating some energy.
  12. Jun 26, 2013 #11


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    Yes sorry for my earlier post. I can't edit it now. I'd just read one too many "water for fuel" crack pot ideas that day.
  13. Jun 28, 2013 #12
    yes i understand, and i am almost confident the ..water for fuel.. they meant is the gas based fuel not the liquid form.
  14. Nov 16, 2013 #13
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