Analytical chemistry-Class 10

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Analytical Chemistry
Analytical Chemistry

Analytical chemistry is the branch of Chemistry where we detect the presence of ions.

After completion of this chapter don’t forget to complete the Practice Set(CLICK)

List of cations and anions forming colourless salts.

CationsAnions
NH4+, Na+, K+, Ca2+, Mg2+, Al3+, Pb2+, Zn2+CO32-, HCO3, SO42-, Cl, CH3COO, Br, O2_, NO3, HSO3, HSO4, S2-, SO32-, PO43-

Cations forming coloured salts

CationSolidSolution
Cu2+BlueBlue
Fe2+Light greenLight green
Fe3+Yellow to brownYellow
Ni2+GreenGreen
Cr3+Bluish green to violetBluish green
Mn2+Light pinkLight pink
Co2+Violet to pinkPink

Anions forming coloured salts

AnionSolidSolution
CrO42-YellowYellow
Cr2O72-OrangeOrange
MnO4Purple with greenish lustrePurple
MnO42-PurplePurple

Colour of some important compounds

CompoundColour
PbS, HgS, Ag2S, FeS, CoS, NiS, FeO, Fe2O3, MnO2, CoO, NiO, CuS, PbO2Black
HgO, HgI2, Pb3O4, Cu2ORed
FeCl3, CdS, PbO, AgIYellow
Ca(OH)2, Mg(OH)2White
Zn(OH)2, Al(OH)3Gelatinous White
Pb(OH)2Chalky white
Fe(OH)2Dirty green
Fe(OH)3Reddish brown
Cu(OH)2Pale blue
Na2ZnO2, Na2PbO2Colourless solution
  

Action of NaOH solution

SaltReactionColour of the ppt.Effect of excess NaOH on the ppt.
Ca2+CaCl2 + 2NaOH → Ca(OH)2 ↓+ 2NaClWhiteInsoluble
Zn2+ZnCl2 + 2NaOH → Zn(OH)2 ↓+ 2NaCl Zn(OH)2 + 2NaOH → Na2ZnO2 + 2H2OGelatinous WhiteColourless solution
Pb2+Pb(NO3)2 + 2NaOH → Pb(OH)2 ↓ + 2NaNO3 Pb(OH)2 + 2NaOH → Na2PbO2 + 2H2OChalky WhiteColourless solution
Fe2+FeSO4 + 2NaOH → Fe(OH)2 ↓+ Na2SO4Dirty greenInsoluble
Fe3+FeCl3 + 3NaOH → Fe(OH)3 ↓+ 3NaClReddish brownInsoluble
Cu2+CuSO4 + 2NaOH → Cu(OH)2 + Na2SO4Pale BlueInsoluble

Action of NH4OH solution

SaltReactionColour of the ppt.Effect of excess NaOH solution on the ppt.
Ca2+
Zn2+ZnCl2 + 2 NH4OH → Zn(OH)2 ↓+ 2 NH4Cl Zn(OH)2 + (NH4)2SO4 +  2 NH4OH → [Zn(NH3)4]SO4+ 4H2O                     Tetrammine zinc sulphateGelatinous WhiteColourless Solution
Pb2+Pb(NO3)2 + 2 NH4OH → Pb(OH)2 ↓ + 2 NH4NO3Chalky WhiteInsoluble
Fe2+FeSO4 + 2 NH4OH → Fe(OH)2 ↓+ (NH4)2SO4Dirty greenInsoluble
Fe3+FeCl3 + 3 NH4OH → Fe(OH)3 ↓+ 3 NH4ClReddish brownInsoluble
Cu2+CuSO4 + 2 NH4OH → Cu(OH)2 + (NH4)2SO4 Cu(OH)2 + (NH4)2SO4 +  2 NH4OH → [Cu(NH3)4]SO4+ 4H2O                     Tetrammine copper sulphatePale BlueInky blue solution

For complete Detection of the ions you may also visit: Test for Cation