I have tried dissolving MgCl2.6H2O in water (100ml). Failing that, I tried dissolving the compound on a heat block...failing that (!!) i tried pH'ing whilst dissolving....nothing works! But I'm told that the solution can definately be made - but how??? Any ideas??
2006-11-17 08:05:51 · 0 answers · asked by Curious kitten! 2 in Science & Mathematics ➔ Chemistry
By the way, I need to make 4.5M MgCl2 (its for the elution stage of an affinity chromatography procedure)
2006-11-17 08:41:04 · update #1
According to Sigma-Aldrich the solubility of MgCl2.6H2O is 1M at 20C (or 20.3030 g/100ml solution), so it shouldn't be possible to prepare 4.5 M MgCl2 in just water. If there are more solutes involved which might increase the solubility of MgCl2 try dissolving those first and then the MgCl2.
Yet I saw some papers using 4.5 or 2.5 M...
I don't know why there is this discrepancy between sigma-aldrich and the solubility provided in the link in the above answer which would correspond to 8 M if you consider 100ml of solution and not water. In reality you would have a significant change in volume when you add so much salt and the solubility would be much less but I don't know exactly how much. If you consider 167g of MgCl2.6H2O then you are adding 88.8 g of water which means that the total volume is at least 189 ml and thus the maximum concentration is 4.3 M.
Wikipedia gives a different number; 54.2g/100ml at 20C, without specifying if it is for the anhydrous or hexahydrate... so it would be 5.6 or 2.6M respectively...
What a mess !!!
Maybe you should also post the question in biology, since someone who has been doing such purifications can clarify the issue.
Another idea would be to prepare a 100ml saturated solution according to the lowest reported solubility (that of sigma-aldrich) using a 250 ml volumetric cylinder, and then from a pre-weighed amount of MgCl2.6H2O keep adding powder slowly until it doesn't dissolve any more. Weigh the powder that is left in order to find how much you dissolved, measure the final volume and calculate the molarity. If you achieve higher than 4.5 M, dilute.
OR
prepare a 4 M if the amount of powder that you couldn't dissolve is very small.
or
prepare 450ml of 1M and evaporate to 100ml of solution while praying that there will be no precipitation...
That's very desperate but I am running out of ideas...
I must say the whole story is very fishy (finding very different solubility values)
I'd go mad too...
2006-11-17 21:53:18 · answer #1 · answered by bellerophon 6 · 0⤊ 0⤋
Magnesium Chloride Sigma
2016-12-29 18:40:04 · answer #2 · answered by loewenstein 4 · 0⤊ 0⤋
Magnesium Chloride Hexahydrate
2016-09-29 02:49:04 · answer #3 · answered by ? 4 · 0⤊ 0⤋
RE:
How do I dissolve Magnesium chloride (hexahydrate)? Its so hard!!?
I have tried dissolving MgCl2.6H2O in water (100ml). Failing that, I tried dissolving the compound on a heat block...failing that (!!) i tried pH'ing whilst dissolving....nothing works! But I'm told that the solution can definately be made - but how??? Any ideas??
2015-08-04 05:46:01 · answer #4 · answered by Fransisco 1 · 1⤊ 0⤋
The solubility in water should be 167g/100ml water @ 20C
http://avogadro.chem.iastate.edu/CHEM211L/MSDS/HydratedMagnesiumChloride.htm
2006-11-17 08:19:08 · answer #5 · answered by Anonymous · 2⤊ 0⤋