aluminium sulphate

Post by **RosalieM** » 23 May 2007, 12:51

Any clues on how to dissolve aluminium sulphate to make up a 1M stock solution? We already have some so i assume it can be done!
Rosalie

Jazz · Post by **Jazz** » 23 May 2007, 13:06

hi,
are you sure you need 1M solution, recomended bench strength is 0.1M
Aluminium sulfate (18H2O):
Molecular weight: 666.45
Strength: 1M
Volume 0.5L
666.45*1*0.5 =333.225gr
Aluminium Sulfate (16 H2O)342.1
342.1*1*.5 = 171.05gr

,
Dissolve Aluminium sulfate in distil water and make up to 0.5L (or as much as you need).
Formulae to use it is M*Mr*V
M is molarity
Mr Molecular weight
V is volume

Lyn · Post by **Lyn** » 24 May 2007, 02:24

RosalieM,

Aluminium Sulfate 0.1M

Dissolve 67g of aluminium sulfate in distilled water and make up to 1 litre of solution.

The use of a magnetic stirrer will assist the dissolving process.

* The above is a plain english explanation for the chemically challenged.

Lyn.

smiley · Post by **smiley** » 24 May 2007, 10:46

I got asked to make a 1M solution once. It is impossible to dissolve, not to mention it uses almost a whole jar to make 500ml. The volume of Aluminium Sulphate powder is almost more than the water you want to add to it. Bad enough trying to get 67g to dissolve!

Kristin

Post by **RosalieM** » 24 May 2007, 11:29

Hey guys,
Thanks for your answers. I guess I didn't say it very clearly. It was more getting it to dissolve rather than the mathematical side... Sorry! I am glad someone else has had trouble with this. I wonder what the bottle of 1M aluminium sulfate really contains? I just started out trying to make 100ml to see if it would dissolve given the need to use so much for a 1M solution. I'll just make it up to a 0.1M solution and hope I never need the other!
Rosalie