Australia's Science Forum

Hi
Does anyone have success when filtering Barium Sulfate? We use Buchner Funnels with the filter paper for barium sulfate from Sc Supply and vacuum pumps on taps but we still don't seem to have success as the sulfate goes through the paper and the solution in the side arm flask is always milky.

We use Gooch crucibles with the side arm flasks and vacuum pumps and have had great success. The gooch crucible is a sintered glass crucible with a porcelain filter in the bottom. I think the No.4 is what you need. They are expensive but have always worked for us.

Buy Whatman filter papers - No 40 could be the one you need but ask the supplier. They are expensive.

I was going to suggest Whatman Grade 42 filters.
Mother

We have good results using Chemistry Contexts 2nd edition prac 3.2 which uses a 0.1% agar solution as a coagulant.

It says " The BaSO4 precipitate is exceedingly fine and is extremely difficult to filter without the uses of agar solution as a coagulating agent. The procedure is valid because the filtrate is clear of any BaSO4 and any agar retained with the BaSO4 residue is of immeasurable mass. If all of the agar was retained, it would add 0.01g to the BaSO4 residue. The sensitivity of the standard laboratory electronic balance is 0.01g"

Hope this helps....

Loopy is it possible to get a copy of that prac?

I will try. My IT capabilities rate very low!....

Here goes, sorry about the writing on the pages....

Thanks Loopy it worked a treat!!

Thanks indeed!

Hi Loopy
Is it possible to have a copy of the "Barium Sulfate /Agar" prac too.
Thanks
Glenpaul

Hi all,
I hope the prac works well for those who try it. Glenpaul, I think the pdf is till available on this page for you to download. Let me know if there are any problems.