5.3.2 - Qualitiative Analysis

Question 1

What order do you test for negative ions?

Answer 1

Carbonate ions, sulphate ions, halogen ions.

Question 2

What order do you test ions for positive ions?

Answer 2

Transition metal ions, ammonium ions.

Question 3

What is the test for carbonate ions?

Answer 3

Add any acid and effervescence will appear due to CO2 being produced.

Question 4

How can you double check for carbonate ions?

Answer 4

Bubble the gas through lime water - turns cloudy.

Question 5

How do you test for sulphate ions?

Answer 5

Add HCl to remove carbonate ions, then add barium chloride solution - white precipitate as barium sulphate is insoluble.

Question 6

How do you test for halogens?

Answer 6

Add nitric acid to remove carbonate ions then add silver nitrate solution. Precipitate will be formed.

Question 7

Chloride

Answer 7

White precipitate which dissolved in dilute NH3

Question 8

Bromide

Answer 8

Cream precipitate which dissolves in concentrated NH3

Question 9

Iodide

Answer 9

Pale yellow precipitate which is insoluble in any NH3 solution.

Question 10

How do you test for transition metal ions?

Answer 10

Add sodium hydroxide solution.

Question 11

Cu2+

Answer 11

Pale blue ppt

Question 12

Mn2+

Answer 12

Brown ppt

Question 13

Fe2+

Answer 13

Green ppt

Question 14

Fe3+

Answer 14

Rusty brown ppt

Question 15

Cr3+

Answer 15

Green ppt

Question 16

How do you test for ammonium ions?

Answer 16

Add sodium hydroxide solution and heat gently. The gas produced will make damp red litmus paper turn blue as gas is NH3.