[ogi]

Hi, I'm not chemical and I'm trying to build a thermal storage system which needs CaCl2.6H2O but I have only CaCl2 (anhydrous), ¿ does somebody knows if it's possible to convert the anhydrous in  CaCl2.6H2O and how ?

Thanks in advance, I've googled the answer a lot without success.

Ogi

[Borek]

Hi, I'm not chemical and I'm trying to build a thermal storage system which needs CaCl2.6H2O but I have only CaCl2 (anhydrous), ¿ does somebody knows if it's possible to convert the anhydrous in  CaCl2.6H2O and how ?

All you have to do is to add correct amount of water.

[ogi]

Hi, I've mixed CaCl2 anhydrous with wather in a proportion 1:2, I guess it should be enough water and taked the solution to 40°C but at cooling there are too few cristals at the bottom indicating that CaCl2.6H2O has not been formed ¿is this conclusion correct ?

Thanks again,

Ogi

[Borek]

You need mass ratio 1:1.

[Donaldson Tan]

this is just crystal growing. prepare a saturated solution of CaCl₂ for crystallisation, Suspend a button inside the solution and warm the solution mildly. You should observe crystal formation on the button.

I guess u been googling the wrong things. Google for "how to grow crystals"

[ogi]

After talking with the provider, my product resulted to be CaCl2.4H2O and not CaCl2 anhydrous, so I guess that was one of my problems, beeing the other the concentration.
I'm doing a new test with a mixture of 250 Gr. of CaCl2.4H2O + 87 Grm H2O that uppon my calculations should be a relation of 1:1 in mass. Thanks a lot for all the info.

I have another question, this is more dificult, I have read that for the solution of CaCl2.4H2O +2H2O converts to CaCl2.6H2O I have to put some Sr(OH)2 acting as "seeding crystal" I don't undestand the reaction and I don't know how much Sr(OH) I need for a 1KG of CaCl2.4H2O.

Besides that, there is last question about if can replace the SR(OH)2 with Strontium Chloride + Sodium Hydroxide because I can't get Sr(OH)2 but I can get  Strontium Chloride or Strontium nitrate.

Thanks a lot guys

Olgierd

[Borek]

If what you have is CaCl₂^.4H₂O mass ratio should be not 1:1 but 183:36 (250:87 is close enough).

If you add stoichiometric amount of water (ie not excess water to dissolve CaCl₂) you don't need seeding crystals.

My knowledge about CaCl₂ hydrates is rather limited, however, I would expect them to be stable only in some humidity/temperature ranges (as all hydrates are). Thus once you will prepare your hydrate you need to keep it in closed jar, as it may easily loose/gain water and change composition.