Qualitative Analysis

Question 1

Name 3 common anions

Answer 1

Carbonate, sulfate and halide

Question 2

How do you test for carbonate ions?

Answer 2

Add diluted HNO3 and any gas through limewater and positive if white precipitate (CaCO3)

Question 3

The equations for the testing of carbonate ions

Answer 3

CO3 2- + 2H+ ———-> CO2 + H2O

Ca(OH)2 + CO2 ———-> CaCO3 + H2O

Question 4

How do you test for sulfate ions?

Answer 4

Make a solution of the sample and add drops of barium nitrate solution and positive result if white precipitate (barium sulfate)

Question 5

The equation for the testing of sulfate ions

Answer 5

Ba 2+ + SO4 2- ———-> BaSO4

Question 6

How do you test for halide ions?

Answer 6

Add drops of silver nitrate solution and then aqueous ammonia

Question 7

Name a cation

Answer 7

Ammonium ion

Question 8

How do you test for ammonium ions?

Answer 8

Add warm NaOH solution and test any gas with damp red litmus paper - if blue, means gas is alkali (ammonia gas)

Question 9

Equation for the testing of ammonium ions

Answer 9

NH4+ + OH- ———-> NH3 + H2O