Required Practical 4

Question 1

What are the tests for group 2 metal cations?

Answer 1

0.6 M NaOH
> with chlorides/calcium bromide
> Ba = colourless
> others = white ppt

1 M H2SO4
> Mg = colourless
> others = white ppt

Question 2

What is the test for ammonium ions?

Answer 2

0.4 M NaOH
> NH4Cl
> water bath
> turns damp red litmus blue

Question 3

What is the test for OH- (aq) ions?

Answer 3

0.4 M NaOH
> turns red litmus blue

1 M NH3 (forms OH with H2O)
> inside petri dish
> turns damp red litmus blue

Question 4

What is the test for CO3 (2-) (aq) ions?

Answer 4

1 M HCl
> combine with Na2CO3
> bubble through limewater
> turns cloudy

Question 5

What is the test for SO4 (2-) (aq) ions?

Answer 5

Dilute HCl + 0.1 M BaCl2
> white ppt

Question 6

What is the test for halide (aq) ions?

Answer 6

Dilute HNO3 + 0.05 M AgNO3
> potassium compounds
> Cl = white ppt
> Br = cream ppt
> I = pale yellow ppt (no dissolving)
> use dilute + concentrated ammonia

Question 7

What is the test for halide (s) ions?

Answer 7

Concentrated H2SO4
> potassium compounds
> Cl = white steamy fumes
> Br = orange fumes
> I = purple fumes + solid
> turn blue litmus red