testing-and-identifying-anions-1214835648531311-8.ppt

Analytical Chemistry

1. Testing and Identifying Halide
Ions
Aim:To identify the conclusive
chemical tests for Halide ions.

2. Chloride Cl
-1
;Bromide Br
-1
;Iodide I
-1
•Add about 2ml of aqueous chloride to a test tube
•Add an equal volume of dilute HNO
3
•Add a few drops of silver (I) nitrate to the tube
•Pour half of the contents of the tube into a clean test
tube
•To the 1
st
tube add dilute ammonia until no further
change
•To the second tube add CONC AMMONIA until there
is no further change – Do this in a fume cupborad
•Repeat with aqueous solutions of bromide and iodide

3. Results Table
Halide Ion
HNO
3
then
AgNO
3
Action of dilute NH
3 on
product
Action of conc NH
3
on
product
Cl
-1
Br
-1
I
-1

4. Results Table
Halide Ion
HNO
3
then
AgNO
3
Action of dilute NH
3 on
product
Action of conc NH
3
on
product
Cl
-1
White ppt
White ppt dissolves
Br
-1
I
-1

5. Results Table
Halide Ion
HNO
3
then
AgNO
3
Action of dilute NH
3 on
product
Action of conc NH
3
on
product
Cl
-1
White ppt
White ppt dissolves
White ppt
dissolves
Br
-1
I
-1

6. Results Table
Halide Ion
HNO
3
then
AgNO
3
Action of dilute NH
3 on
product
Action of conc NH
3
on
product
Cl
-1
White ppt
White ppt dissolves
Br
-1
Cream ppt
I
-1

7. Results Table
Halide Ion
HNO
3
then
AgNO
3
Action of dilute NH
3 on
product
Action of conc NH
3
on
product
Cl
-1
White ppt
White ppt dissolves
Br
-1
Cream ppt No reactionCream ppt
dissolves
I
-1

8. Results Table
Halide Ion
HNO
3
then
AgNO
3
Action of dilute NH
3 on
product
Action of conc NH
3
on
product
Cl
-1
White ppt
White ppt dissolves
Br
-1
Cream ppt Insoluble Cream ppt
dissolves
I
-1
Yellow pptInsoluble insoluble

9. Ionic Equations for the reaction
•Sodium chloride + Silver nitrate
•NaCl + AgNO
3
•Repeat for Sodium Bromide and Silver iodide as above

10. Sulphate SO
4
2-
and Sulphite SO
3
2-
Place 2ml of aqueous sulphate in a
test tube.
Add a few drops of barium
chloride
Add 1ml of HCl Dilute and shake
the mixture vigorously
Leave the tube to stand
Repeat the experiment with a sample
of aqueous sulphite – do in fume cup
board, Test the gas evolved with
acidified dichromate paper

11. Results Table
AnionsAction of BaCl
2
followed by HCl
SO
4
2-
SO
3
2-

12. Results Table
AnionsAction of BaCl
2
followed by HCl
SO
4
2-
White ppt of BaSO
4 that does not
redissolve in acid
SO
3
2-
Gas evolved with pungent odour – SO
2..
It turns acid dichromate paper from
orange to green ( test for SO
2
)

13. Carbonate CO
3
2-
and Hydrogen
Carbonate HCO
3
-1
Add 1 ml of sodium carbonate to a
test tube – add a few drops of HCl
Repeat the experiment with aqueous
potassium hydrogen carbonate
Record the results in the table
Add a few drops of Barium chloride

14. Results
Anion Reaction with HCl followed by Barium
chloride
CO
3
2-
HCO
3
-1

15. Results
Anion Reaction with HCl followed by Barium
chloride
CO
3
2-
Gas evolved – CO
2
White ppt formed
HCO
3
-1
Gas evolved – CO
2
No ppt formed

16. Nitrate ion NO
3
-1
Place together in a test tube a
small amount of sodium nitrate (V)
and a piece of Al foil.
Add about 5ml of aqueous sodium
hydroxide solution
If no reaction takes place – carefully
warn the tube in a water bath
Test the gas evolved using damp red
litmus paper

17. Results table
IonObservation
NO
3
-1
Pungent gas evolved.
Turns red litmus blue – Alkaline gas –
Ammonia.
Formed by the reduction of the nitrate ion.

18. Summary of results
Name of ion FormulaTest Result
Chloride
Bromide
Iodide
Sulphate
Sulphite
Carbonate
Hydrogen carbonate
Nitrate

19. Summary of results
Name of ion FormulaTest Result
Chloride Cl
-1
Bromide Br
-1
Iodide I
-1
Sulphate (IV) SO
4
2-
Sulphite (VII) SO
3
-1
Carbonate CO
3
2-
Hydrogen carbonateHCO
3
-1
Nitrate NO
3
-1

20. Summary of results
Name of ionFormula Test Result
Chloride Cl
-1
Acidified silver nitrate
Solubility with ammonia
White ppt of
AgCl soluble
in dil NH
3
Bromide Br
-1
Acidified silver nitrate
Solubility with ammonia
Cream ppt of
AgBr soluble
in conc NH
3
Iodide I
-1
Acidified silver nitrate
Solubility with ammonia
Yellow ppt of
AgI insoluble
in excess NH
3
Sulphate (IV)SO
4
2-
Sulphite (VII)SO
3
-1
Carbonate CO
3
2-
Hydrogen
carbonate
HCO
3
-1
Nitrate NO
3
-1

21. Summary of results
Name of ionFormula Test Result
Chloride Cl
-1
Acidified silver nitrate
Solubility with ammonia
White ppt of AgCl
soluble in dil NH
3
Bromide Br
-1
Acidified silver nitrate
Solubility with ammonia
Cream ppt of AgBr
soluble in conc NH
3
Iodide I
-1
Acidified silver nitrate
Solubility with ammonia
Yellow ppt of AgI
insoluble in excess
NH
3
Sulphate (IV)SO
4
2-
Solution of barium chloride or
nitrate.If ppt forms add dil HCl
White ppt of BaSO
4
insoluble in acid
Sulphite (VII)SO
3
-1
As above Gas evolved
SO2.Test with
dichromate paper
turning from orange
to green,

22. Summary of results(2)
Name of ionFormula Test Result
Carbonate CO
3
2-
Hydrogen
carbonate
HCO
3
-1
Nitrate NO
3
-1

23. Summary of results(2)
Name of ionFormula Test Result
Carbonate CO
3
2-
Dilute HCl followed by BaCl
2
Hydrogen
carbonate
HCO
3
-1
Dilute HCl followed by BaCl
2
Nitrate NO
3
-1

24. Summary of results(2)
Name of ionFormula Test Result
Carbonate CO
3
2-
Dilute HCl followed by BaCl
2
White ppt of BaCO
3
formed and gas
evolved
Hydrogen
carbonate
HCO
3
-1
Dilute HCl followed by BaCl
2
Gas evolved
No ppt.
Nitrate NO
3
-1

25. Summary of results(2)
Name of ionFormula Test Result
Carbonate CO
3
2-
Dilute HCl followed by BaCl
2
White ppt of BaCO
3
formed and gas
evolved
Hydrogen
carbonate
HCO
3
-1
Dilute HCl followed by BaCl
2
Gas evolved
No ppt.
Nitrate NO
3
-1
Add Al and dil NaOH

26. Summary of results(2)
Name of ionFormula Test Result
CarbonateCO
3
2-
Dilute HCl followed by BaCl
2
White ppt of
BaCO
3
formed
and gas evolved
Hydrogen
carbonate
HCO
3
-1
Dilute HCl followed by BaCl
2Gas evolved
No ppt.
Nitrate NO
3
-1
Add Al and dil NaOH Gas evolved –
turns red litmus
blue – alkaline
gas – NH
3 from
the reduction of
NO2

27. Name the Salt
•An unknown salt is dissolved in distilled water to
make an aqueous solution. Sodium hydroxide is
added to the solution and a green precipitate is
formed that dissolves in sodium hydroxide to
form a dark green solution.
•When HCl is added to the solid a gas is evolved.
When barium chloride is added to the solution a
white ppt is formed
•Name the salt
•Write the chemical formula for this chemical
Chromium (III) Carbonate
Cr
2(CO
3)
3