Notices
Results 1 to 12 of 12

Thread: Phase Change Material

  1. #1 Phase Change Material 
    New Member
    Join Date
    Oct 2017
    Posts
    4
    can i change anhydrous Sodium Sulfate into Sodium Sulfate Decahydrate?


    Reply With Quote  
     

  2.  
     

  3. #2  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    2,616
    Quote Originally Posted by fareeha View Post
    can i change anhydrous Sodium Sulfate into Sodium Sulfate Decahydrate?
    Yes.

    But this not a phase change. It is a chemical reaction. This is because the starting materials (Na2SO4 , H2O) are not the same as what you have at the end (Na2SO4.10H2O).


    Reply With Quote  
     

  4. #3  
    Forum Professor Zwolver's Avatar
    Join Date
    May 2006
    Location
    Netherlands
    Posts
    1,632
    Quote Originally Posted by exchemist View Post
    But this not a phase change. It is a chemical reaction. This is because the starting materials (Na2SO4 , H2O) are not the same as what you have at the end (Na2SO4.10H2O).
    I thought it was a crystalline structural change, not a chemical reaction. Hmm..

    Is calculating how much H2O is needed, and adding enough watervapor, good enough to change the crystalline structure this way?
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

    Imagine, being able to create matter out of thin air, and not coming up with using drones for boarding hostile ships. Or using drones to defend your own ship. Heck, using drones to block energy attacks, counterattack or for surveillance. Unless, of course, they are nano-machines in your blood, which is a billion times more complex..
    Reply With Quote  
     

  5. #4  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    2,616
    Quote Originally Posted by Zwolver View Post
    Quote Originally Posted by exchemist View Post
    But this not a phase change. It is a chemical reaction. This is because the starting materials (Na2SO4 , H2O) are not the same as what you have at the end (Na2SO4.10H2O).
    I thought it was a crystalline structural change, not a chemical reaction. Hmm..

    Is calculating how much H2O is needed, and adding enough watervapor, good enough to change the crystalline structure this way?
    It is reacting with water and producing a new chemical compound, a hydrated form of the salt. So it is not just a new crystal structure of the same substance, but a different substance. There is an associated enthalpy of formation, which I believe is sometimes used for (rather bad) classroom determinations.

    I do not know how quickly anhydrous Na2SO4 take up water vapour, I'm afraid. Perhaps PhDemon can comment if he reads this.
    Reply With Quote  
     

  6. #5  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    4,496
    It isn't that hygroscopic, what I would do to make the hydrated version is dissolve the anhydrous salt in water and recrystallize it. This will be quicker (and ensure complete conversion) than waiting for it to absorb atmospheric water.
    Reply With Quote  
     

  7. #6  
    New Member
    Join Date
    Oct 2017
    Posts
    4
    Quote Originally Posted by PhDemon View Post
    It isn't that hygroscopic, what I would do to make the hydrated version is dissolve the anhydrous salt in water and recrystallize it. This will be quicker (and ensure complete conversion) than waiting for it to absorb atmospheric water.
    so by simply adding water, salt hydrate would be formed.. but how much water we should add as i want to use it as PCM in storage tank?
    Reply With Quote  
     

  8. #7  
    Bullshit Intolerant PhDemon's Avatar
    Join Date
    Feb 2013
    Location
    Newcastle-upon-Tyne, UK
    Posts
    4,496
    The only way to be sure you are getting 100% conversion is to add enough water to completely dissolve the anhydrous salt, then leave to stand and let the water evaporate. Th e remaining crystals will be the decahydrate.

    Or you could just buy the decahydrate, it's really cheap
    Reply With Quote  
     

  9. #8  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    2,616
    Quote Originally Posted by fareeha View Post
    Quote Originally Posted by PhDemon View Post
    It isn't that hygroscopic, what I would do to make the hydrated version is dissolve the anhydrous salt in water and recrystallize it. This will be quicker (and ensure complete conversion) than waiting for it to absorb atmospheric water.
    so by simply adding water, salt hydrate would be formed.. but how much water we should add as i want to use it as PCM in storage tank?
    What does PCM stand for?
    Reply With Quote  
     

  10. #9  
    New Member
    Join Date
    Oct 2017
    Posts
    4
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by fareeha View Post
    Quote Originally Posted by PhDemon View Post
    It isn't that hygroscopic, what I would do to make the hydrated version is dissolve the anhydrous salt in water and recrystallize it. This will be quicker (and ensure complete conversion) than waiting for it to absorb atmospheric water.
    so by simply adding water, salt hydrate would be formed.. but how much water we should add as i want to use it as PCM in storage tank?
    What does PCM stand for?
    Phase Change Material
    Reply With Quote  
     

  11. #10  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    2,616
    Quote Originally Posted by fareeha View Post
    Phase Change Material
    OK. Why do you want a "phase change material" in a storage tank? What is it supposed to do?
    Reply With Quote  
     

  12. #11  
    New Member
    Join Date
    Oct 2017
    Posts
    4
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by fareeha View Post
    Phase Change Material
    OK. Why do you want a "phase change material" in a storage tank? What is it supposed to do?
    store heat... im talking about thermal storage tank in which PCM store heat and later on can be used for heating purpose
    Reply With Quote  
     

  13. #12  
    exchemist
    Join Date
    May 2013
    Location
    London
    Posts
    2,616
    Quote Originally Posted by fareeha View Post
    Quote Originally Posted by exchemist View Post
    Quote Originally Posted by fareeha View Post
    Phase Change Material
    OK. Why do you want a "phase change material" in a storage tank? What is it supposed to do?
    store heat... im talking about thermal storage tank in which PCM store heat and later on can be used for heating purpose
    Aha, now I see what you want to do. The decahydrate (Glauber's Salt) has a melting point of 32C, so its latent heat of fusion can in principle be used for reversible heat storage...once you have made the decahydrate from the anhydrous version. Or you can just buy Glauber's Salt of course and save yourself the trouble.
    Reply With Quote  
     

Similar Threads

  1. Replies: 0
    Last Post: December 1st, 2012, 12:16 AM
  2. Phase - change cells for heating the green house
    By JustRick in forum General Discussion
    Replies: 0
    Last Post: January 4th, 2012, 04:22 PM
  3. Replies: 7
    Last Post: March 18th, 2011, 08:09 PM
  4. Phase mimicking?
    By Cold Fusion in forum Physics
    Replies: 0
    Last Post: August 14th, 2010, 06:46 PM
  5. Replies: 5
    Last Post: December 24th, 2009, 05:56 PM
Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •