TESTS FOR SO2:
1) acidic K2Cr2O7 turns green
2) color of acidic KMnO4 is discharged
3) Color of I2 soln is discharged
4) Acidic KIO3 or starch paper turns blue
5) Passed in lime water => white turbidity of CaSO3=> excess gas passed => clear soln of Ca(HSO3)2.
TESTS FOR H2S:
1) color of acidic K2Cr2O7 turns green
2) color of acidic KMnO4 is discharged
3) Lead acetate paper turns black
4) Cadmium acetate turns yellow
BROWN RING TEST:
Nitrite+ dil H2SO4 or dil CH3COOH + fresh FeSO4 => brown ring
2NaNO2 + H2SO4 => 2 HNO2 + Na2SO4
3HNO2 => 2NO + HNO3 + H2O
FeSO4 + NO => Fe(NO)SO4
FeSO4 + 5H2O + NO => [Fe(H2O)5NO]SO4
Co+2 salt properties: [Group 4]
Color: pink
It forms a pink soln
Its sulphide is black
It gives yellow ppt with acetic acid and KNO2.
Ni+2 salt properties: [Group 4]
Color: green salt
It forms a green soln
Its sulphide is black
It gives red ppt with dimethyl glycerine in ammonical medium
FLAME TEST:
The chloride salts of Ba+2 and Ca+2 ions are more volatile and flame test is applicable only for volatile salts.The salt is treated with a few drops of conc HCl and a paste is prepared. This is done to convert the metal ions into volatile chlorides. A little of this paste is applied at the tip of platinum wire nd is heated in an oxidizing flame. Barium ions give an apple green flame to it and calcium ions give them brick red flame.
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