A particular anion can be "positively identified" if the presence of that anion is indicated by a reaction that cannot be confused with any other reaction and that cannot be masked (hidden) by any other reaction occurring at the same time.
Suppose that a solution contains four anions: chloride, nitrate, nitrite, and sulfate. Which anions can be positively identified?
A. chloride
B. nitrite
C. sulfate
D. nitrate
Doc Inmaking was careless and didn't stir his reactions. He performed classification tests A, B, and C on an unknown salt containing one of the nine anions used in this lab. For classification test A, he observed a milky white solution when the barium cation was added. The addition of acid caused a white sludge to sink to the bottom of the test tube while the solution on top was clear. For classification test B, there was no reaction. For classification test C, a milky yellow solution formed, but it seemed to fade and settle when the acid was added.
Doc decided to try the confirmation test for halides and observed two colorless layers. Is he correct to conclude that the unknown anion was chloride? What other possible identity would you suggest for the anion?
A. Yes.
B. No.
C. SO42-
D. SO32-
E. CO32-
F. PO43-
G. NO3-
H. NO2-
I. halide (Cl-, Br-, I-)