1. Chemsheets AS006 (Electron arrangement)
21/04/2019
HALIDE ION TESTS

2. IT IS THE SILVER NITRATE SOLUTION THAT REACTS WITH THE SAMPLE SOLUTION
TEST FOR HALIDE IONS (Cl- ; Br- ; I-)
ADD DILUTE NITRIC ACID FOLLOWED BY SILVER NITRATE SOLUTION TO THE SAMPLE SOLUTION
NITRIC ACID IS ADDED TO REMOVE IMPURITES
IT IS THE SILVER NITRATE SOLUTION THAT REACTS WITH THE SAMPLE SOLUTION
A COLOURED PRECIPITATE OF SILVER HALIDES FORM

3. NOTE//
The nitric acid is added to remove CO32- (carbonate ions) and OH- ions (hydroxide ions) which would otherwise precipitate with Ag+ ions and ∴ show incorrect results by masking the desired observations

4. i.e.
HALIDE ION
COLOUR OF PRECIPITATE FORMED
NAME OF PRECIPITATE FORMED
Chloride ion (Cl-)
White
Silver chloride
Bromide ion (Br-)
Cream
Silver bromide
Iodide ion (I-)
Yellow
Silver iodide
Cl-
Br- I-

5. Ionic equations
Below are the ionic equations which describes the precipitation reaction which take place:
The coloured precipitates which form
From the sample
From the silver nitrate
The state symbols
are crucial, as you need to show that the silver halides (AgCl etc) are formed as solids i.e. (s). This is why you see precipitates in the reactions!
Cl-(aq)
Ag+(aq) Ag
Cl(s) +
Br-(aq)
Ag+(aq) Ag
Br(s) +
I-(aq)
Ag+(aq) Ag
I(s) +

6. The main problem with this test is that it is very difficult to distinguish between the precipitate colours particularly between AgBr and AgI so another confirmatory test must be carried out
To carry out a confirmatory test ammonia solution is added

7. Action of dilute NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
Cl–(aq)
Br–(aq)
I–(aq)

8. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate AgF is soluble
Cl–(aq)
Br–(aq)
I–(aq)
© AS July-2015

9. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Br–(aq)
I–(aq)
© AS July-2015

10. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble in dilute NH3(aq)
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Br–(aq)
I–(aq)
© AS July-2015

11. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble in dilute (aq) ammonia
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Soluble in dilute (aq) NH3
Br–(aq)
I–(aq)
© AS July-2015

12. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Br–(aq)
Ag+(aq) + Br–(aq) → AgBr(s)
cream ppt
I–(aq)
© AS July-2015

13. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble in dilute (aq) NH3
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Br–(aq)
Ag+(aq) + Br–(aq) → AgBr(s)
cream ppt
Insoluble in dilute (aq) NH3
I–(aq)
© AS July-2015

14. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble in dilute (aq) NH3
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Br–(aq)
Ag+(aq) + Br–(aq) → AgBr(s)
cream ppt
Insoluble in dilute (aq) NH3
Soluble in conc. (aq) NH3
AgBr(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Br–(aq)
I–(aq)
© AS July-2015

15. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble in dilute (aq) NH3
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Br–(aq)
Ag+(aq) + Br–(aq) → AgBr(s)
cream ppt
Insoluble in dilute (aq) NH3
Soluble conc. (aq) NH3
AgBr(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Br–(aq)
I–(aq)
Ag+(aq) + I–(aq) → AgI(s)
yellow ppt
© AS July-2015

16. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble in dilute (aq) NH3
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Br–(aq)
Ag+(aq) + Br–(aq) → AgBr(s)
cream ppt
Insoluble in dilute (aq) NH3
Soluble in conc. (aq) NH3
AgBr(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Br–(aq)
I–(aq)
Ag+(aq) + I–(aq) → AgI(s)
yellow ppt
© AS July-2015

17. Action of dilute NH3(aq) Action of conc. NH3(aq)
Halide ion
Action of AgNO3(aq)
Action of dilute NH3(aq)
Action of conc. NH3(aq)
F–(aq)
No precipitate
Cl–(aq)
Ag+(aq) + Cl–(aq) → AgCl(s)
white ppt
Soluble in dilute (aq) NH3
AgCl(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Cl–(aq)
Br–(aq)
Ag+(aq) + Br–(aq) → AgBr(s)
cream ppt
Insoluble in dilute (aq) NH3
Soluble in conc. (aq) NH3
AgBr(s) + 2 NH3(aq) →
[Ag(NH3)2]+(aq) + Br–(aq)
I–(aq)
Ag+(aq) + I–(aq) → AgI(s)
yellow ppt
Insoluble in conc. (aq) NH3
© AS July-2015