Gravimetric determination of sulphate in Cr(III) solution

Hello!

Does anyone know a gravimetric method for determination of sulphate in a solution containing approximately 0.5 M Cr(III)? The acidity of the solution is very low (pH<1)and I have tried to precipitate the sulphate as BaSO4 by adding excess (10 ml 10%) BaCl2. However, this hasn't worked. Can anyone tell me what I am doing wrong?

Thank you,

1. Make a solution containing 15 parts isopropyl alcohol, 7 parts HCl, 25 parts glacial acetic acid ⇦ on eBay or Amazon [affil link] .
2. Pipette [pipettes on eBay or Amazon [affil link] 10 ml plating bath into a 400 ml flask. Add 75 ml of the solution from step 1 and boil in a hood for 15-20 minutes.
3. Add 50 ml hot di water and 5 ml of 30% BaCl solution
4. Add 5 ml saturated picric acid solution and let stand for 2 hours.
5. Filter through a preweighed grooch crucible.
6. Dry at 120C to a constant weight.

Weight of filtrate (g) x 42.02 = g/L H2SO4

JIM,

PICRIC ACID HAS BEEN REMOVED, THEN BANNED FROM THE CABINETS OF LABORATORIES SINCE THE LATE 1970'S BECAUSE IT FORMS EXPLOSIVE, PRESSURE SENSITIVE CRYSTALS UNDER THE CAP.