Sulfate tests Flashcards
What are sulfate tests based on?
Precipitate formation
Are most sulphates soluble in water?
Yes
What sulfate can be used to identify sulphates in unknown solutions and why?
Barium sulfate
Very insoluble
What does barium sulfate form when it forms?
White precipitate
Write the ionic equation for barium sulfate formation
Ba2+ (aq) + SO42- (aq) → BaSO4 (s)
What is normally used as a source of Ba2+ ions?
Barium chloride
Barium nitrate
Why do we need to use barium nitrate if we want to do a test for sulfate and a test for halides in one test tube?
Barium chloride would also supply a source of Cl- ions
It is able to react with silver nitrate
Able to form a white precipitate
Gives a false positive for sulphate ions
What is barium carbonate (BaCO3)?
An insoluble white precipitate in water
What else do transition metals also form?
Insoluble carbonate salts
What do we have to eliminate before doing the sulfate test?
The carbonate solution (do the carbonate test first)
The sulphate test is usually which on an unknown?
Second
