C4.2.3 - Detecting Anions

Question 1

What is formed when barium ions react with sulfate ions?

Answer 1

White insoluble barium sulfate

Question 2

Describe how you would detect sulfate ions.

Answer 2

Add a few drops of hydrochloric acid to the solution, then a few drops of barium chloride. If the solution turns white, sulfate ions are present

Question 3

Why does barium sulfate turn white?

Answer 3

A white precipitate is formed

Question 4

What do hydrogen ions from dilute acids react with to form carbon dioxide and water?

Answer 4

Carbonate ions

Question 5

Are most carbonates soluble?

Answer 5

No

Question 6

Describe how you would detect carbonate ions.

Answer 6

Add a few drops of dilute hydrochloric/nitric acid to the solution, if it begins to bubble, carbonate ions are present. You can confirm the gas is carbon dioxide by bubbling it through limewater.

Question 7

Describe how you would detect halide ions.

Answer 7

Add a few drops of nitric acid the solution, then add a few drops of silver nitrate solution. If the solution changes colour, a halide ion is present

Question 8

What is the colour of the precipitate form if chloride ions are present?

Answer 8

white

Question 9

What is the colour of the precipitate form if bromide ions are present?

Answer 9

cream

Question 10

What is the colour of the precipitate form if iodide ions are present?

Answer 10

yellow