Sintered crucible porosity

[ana.santos]

Hi all,
Has anyone done Chem 12 prac on (Sulfate Content of a Fertiliser)? We have problem filtering barium chloride solution as it goes through a sintered crucible porosity 4. I have asked a supplier for a finer filter crucible and there is a porosity 5, still thinking if I will order this as I'm not sure if it will work. Any other suggestions?
Ana

[LabMad]

My HOD uses 'Yates - Sulphate of Iron', I think she got maintainance to get it from bunnings

[lada]

We have used buckner funnel with hand held vacuum pump. It worked better then crucibles, but still depends on quality of paper. We use "slow" 103 for fine crystalline and its fine for students. The recovery will not be 100% but good enough for school pracs.
Hope this will help.
Lada

[rae]

We use the glass gooch crucibles with porosity of 4 for this prac attached to a vacuum flask. Purchased from science supply.
The prac has always worked although we did have a problem with one of the crucibles not forming a proper vacuum so it wouldn't filter.
We have never had the barium sulfate go through the filter.
Sorry this probably doesn't help much.

[sunray18]

Have you tried making a mulch of filter paper? I used to do this in industrial lab.. just blend up your filter paper with distilled water and pour it into buchner - as suction is applied it forms a thick wad... may help!

[ana.santos]

Thank you for all the replies!Will see which one works.