Sulfate tests

Question 1

What are sulfate tests based on?

Answer 1

Precipitate formation

Question 2

Are most sulphates soluble in water?

Answer 2

Yes

Question 3

What sulfate can be used to identify sulphates in unknown solutions and why?

Answer 3

Barium sulfate
Very insoluble

Question 4

What does barium sulfate form when it forms?

Answer 4

White precipitate

Question 5

Write the ionic equation for barium sulfate formation

Answer 5

Ba2+ (aq) + SO42- (aq) → BaSO4 (s)

Question 6

What is normally used as a source of Ba2+ ions?

Answer 6

Barium chloride
Barium nitrate

Question 7

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?

Answer 7

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

Question 8

What is barium carbonate (BaCO3)?

Answer 8

An insoluble white precipitate in water

Question 9

What else do transition metals also form?

Answer 9

Insoluble carbonate salts

Question 10

What do we have to eliminate before doing the sulfate test?

Answer 10

The carbonate solution (do the carbonate test first)

Question 11

The sulphate test is usually which on an unknown?

Answer 11

Second