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Exothermic reaction of zeolite and water

  1. Dec 22, 2015 #1
    So, I was reading about zeolites:
    https://en.wikipedia.org/wiki/Zeolite

    One of the things it is used for, is in the heating industry, namely:
    "Zeolites can be used as solar thermal collectors and for adsorption refrigeration. In these applications, their high heat of adsorptionand ability to hydrate and dehydrate while maintaining structural stability is exploited. This hygroscopic property coupled with an inherent exothermic (energy releasing) reaction when transitioning from a dehydrated to a hydrated form make natural zeolites useful in harvesting waste heat and solar heat energy. Zeolites are also used as a molecular sieve in cryosorption style vacuum pumps.[13]"

    The question is, how hot does the exothermic reaction get? how long the zeolites stay warm in room temperature?
     
  2. jcsd
  3. Dec 22, 2015 #2

    Borek

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    Staff: Mentor

    This isn't the right question. Reaction doesn't "get hot". Reaction mixture or reactants get hot. How hot can it get? Depends on the standard reaction enthalpy and the heat capacity of the mixture.

    Depends on the insulation and external temperature. With some tricks you can keep them at constant temperature (despite reaction being exothermic) or hot for months (after reaction ended).
     
  4. Dec 22, 2015 #3
    Ok let me pin point my question - what is the temperature rise I can expect to get out of 100 grams of dry zeolites and 100ml of water at room temperature, mixed together?
     
  5. Dec 22, 2015 #4

    Borek

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    Staff: Mentor

    A lot depends on the particular zeolite, but to get some rough numbers: quick googling shows this table. Heat capacity of the mixture will be well below that of water - say half of 4.2 J/gK.
     
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