Test for sulfates

Question 1

What does this test for?

Answer 1

SO₄²⁻ ions

Question 2

Step 1

Answer 2

Add dilute hydrochloric acid to test tube of sample

Question 3

Why add dilute hydrochloric acid?

Answer 3

To remove unwanted carbonate ions which would produce a precipitate and give a false positive

Question 4

Step 2

Answer 4

Add barium chloride drops to sample

Question 5

Why add barium chloride?

Answer 5

Because then the barium ions can react with sulfate ions (if a positive result) in solution to form barium sulfate:
BaSO₄

Question 6

Positive result

Answer 6

A white precipitate of BaSO₄ is formed which is insoluble in water