hi, so we had a general anion unknown to do that may contain 5 of the following: carbonate, sulfite, chloride, bromide, iodide, oxalate, chromate, sulfide, sulfate, phosphate, nitrate, nitrite, chlorate, acetate, and thiocyanate. I am positive that my unkown had phosphate, iodide, and thiocyanate, and when i tested for sulfate i removed iodide and thiocyanate, removed excess silver ion from past steps by precipitating it out with NaCl, made the soln acidic, added CaCl2, then i added BaCl2 and got NO PRECIPITATE. But then i used another method which was add AgNO3 to my unknown, centrifuge, add HNO3 to the soln, then add BaCl2, and i got a white fluffy precipitate that was insoluble in 6M HNO3, 12M HCl and i heated it in a water bath and it did not dissolve. so my question is did i have sulfate? or could i have reduced/oxidized thiocyanate to sulfate in that step? but i dont think i used any oxidizing/reducing agents in that step, or could it have been some other ppt..??