1. Tests for Anions Need to know test for Chloride Sulfate/sulfite
carbonate/hydrogen carbonate
nitrate
phosphate
(NB know confirmatory test too!)

2. Chloride Add AgNO3 Get white ppt Confirm = ppt dissolves in
dilute ammonia
Equation needed
Ag+ + Cl -  AgCl ()

3. Sulfate/sulfite Add BaCl2 Get
white ppt with both sulfate and with sulfite
To Distinguish you…
add
dil HCl to white ppt
ppt remains = sulfate
ppt dissolves = sulfite (sulfite doesn’t stay white)
Equation needed !!

4. Sulfate/sulfite Equations With barium chloride
Ba2+ + SO4 2-  BaSO4 ()
Ba2+ + SO3 2-  BaSO3 ()
Distinguishing test
BaSO4 + HCl  no reaction
BaSO3
SO H+  SO2 + H20 (ppt dissolves)

5. CO32- /HCO3- Add dil. HCl (or any acid) Get
bubbles of CO2 (limewater milky) with each
To Distinguish you….
add
MgSO4 to fresh solution
white ppt. immediately = carbonate
white ppt on heating = hydrogen carbonate
Equation needed !!

6. CO32- /HCO3- EQUATIONS With dilute HCl CO32- + 2H +  CO2() + H2O
HCO3- + H +  CO2() + H2O
Limewater
Ca(OH)2 + CO2  CaCO3 () + H2O
Milky white

7. CO32- /HCO3- Distinguishing test Mg 2+ + CO32-  MgCO3 () white
Mg 2+ + HCO3-  Mg(HCO3- )2 soluble
Mg(HCO3- )  MgCO3 () + CO2() + H2O (when heated)

8. Nitrate Brown Ring Test Add fresh FeSO4
At slant add conc. H2SO4 drop wise
Get
brown ring at junction of 2 layers
No equation needed

9. Phosphate Add ammonium molybdate 5 drops of conc. nitric acid
(warm the solution in water bath 40oC)
Get yellow ppt
No equation needed
Confirm: Goes colourless when add dilute NH3

10. Why do we need to know?
Nitrates and phosphates are present in fertilisers and detergents
Excess nitrates & phosphates runoff into rivers and lakes
This fertilises the algae – causing algal bloom – lake goes green
Algae die
Dead algae are decomposed by aerobic bacteria
This uses up oxygen
Fish and other animals die
Eutrophication = excess nutrients in water

11. Questions You add ammonium molybdate when testing for ? Phosphates
You add silver nitrate when testing for ?
Chlorides
You use Magnesium sulfate for?
Distinguishing between carbonates and hydrogencarbonates
(white ppt formed immediately means carbonate)

12. Questions BaCl2 is used to test for which two anions?
Sulfates and sulfites
You add conc.nitric acid when testing for ?
phosphates
You add dilute HCl in which 4 anion tests
Gives CO2 with both carbonates and hydrogencarbonates
As distinguishing test for sulfates and sulfites – both gave white ppt with BaCl2
(sulfate – ppt unchanged)

13. Questions AgNO3 is used to test for ? Chloride
You add conclusion can you draw if a white ppt forms when BaCl2 is added to a solution ?
Solution is either a sulfate or sulfite
What is the confirmatory test for phosphates?
The yellow ppt(from addition of ammonium molybdate, conc HNO3 and gentle heating ) dissolves in dilute ammonia solution (NH4OH)

14. The End!