need help with salts - CaCl2+6H2O

ok guys, I bought some CaCl2, but mine has this written on the bottle: CaCl2+6H2O

when I asked the guy in the store, he said that it's pure CaCl2 with 6 molecules of H2O attached to it

can I still use this for my brewing water?

thanks

yep. Use the right formula weight and you'll have no problem achieving your desired calcium concentration.

Rushis said:

yep. Use the right formula weight and you'll have no problem achieving your desired calcium concentration.

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you mean just to input the data in the calculator as usual?

I'm a little bit worried about this, don't know why.... What does it mean anyway "6 molecules of H2O attached to it..." and how does it affect my water?

Calcium chloride hexahydrate. It's just calcium chloride with a little water in it . It is used the same as regular CaCl2.

shutupjojo said:

Calcium chloride hexahydrate. It's just calcium chloride with a little water in it . It is used the same as regular CaCl2.

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are you completely sure about it? because this is the explanation that I have got from a friend:

- molecular mass of CaCl is approx. 111
- molecular mass of 6H2O is approx. 108 (six molecules x 18 = 108)

overall weight of 1 molecule Calcium chloride hexahydrate is 111+108=219

so we need to determine how much of pure CaCl is in one molecule of Calcium chloride hexahydrate:

111/219=0,5068*100=50,68%

this means that I should add double amount

any thoughts on this?

When calcium chloride crystalizes some water molecules are incorporated into the crystal lattice. For each calcium ion there are a pair of chlorine ions and 0, 1, 2, 4, or 6 molecules of water. This is referred to a "water of hydration". Your friend is quite right. The atomic weight of calcium is 40 and that of chlorine 35.45. Each water molecule has a molecular weight of 18 and there are six of them in the hexahydrate so a mole of CaCl2.6H2O has molecular weight of 40 + 2*35.45 + 6*18 = 218.90 (approximately). Of these 219 grams 40 are calcium so the percentage calcium is 40/219 = 18.27%. The amount of chloride is 70.9/219 = 32.4%.

Have a look at http://en.wikipedia.org/wiki/Calcium_chloride. They list the molecular weights of all the forms and you can use those to determine how many grams of hexahydrate are required to provide the same amount of calcium as 1 gram of the anhydrous (no water) i.e. 219.08/110.98 = 1.9740. Etc.