Experiment 9.1: Confirmatory Test for Anions

Gray/Black ppt

Hg₂(NO₃)₂ + HNO³ + Cl^- = Hg₂Cl₂ to Hg⁰

Gray/Black ppt

Hg₂(NO₃)₂ + HNO₃ + CN^- = Hg₂(CN)₂ to Hg⁰

Blood red solution

FeCl₃ + SCN^- = Fe(SCN)²⁺

Prussian Blue

FeCl₃ + Fe(CN)₆^4- = Fe₄[Fe(CN)₆]₃

Turnbull’s Blue

Fe(CN)₆^3-+ FeSO₄ = Fe₃[Fe(CN)₆]₂

brown vapor with brown or orange layer

Br^- + KMnO₄, H₂SO₄, CH₃Cl = Br₂

violet vapor with violet or purple layer

I^- + KMnO₄, H₂SO₄, CH₃Cl = I₂

Violet vapor and dark blue

I^- + CH₃COOH, NaNO₂, starch solution = I₂

colorless gas with rotten egg odor

S^2- + conc. H₂SO₄ = H₂S↑

black ppt

S^2- + Pb(CH₃COO)₂ = PbS

colorless gas

NO₂^- + Urea in HCl = N₂, CO₂↑

brown ring at the junction of 2 liquids

NO₂^- + FeSO₄ + CH₃COOH = FeNOSO₄, [Fe(NO)]⁺²

vinegar odor

CH₃COO^- + conc. H₂SO₄ = CH₃COOH

fruity odor

CH₃COO^- + C₂H₅OH = CH₃COOC₂H₅

brown solution

CH₃COO^- + FeCl₃ = Fe(CH₃COO)₃

reddish brown ppt

CH₃COO^- + FeCl₃ + boiling = CH₃COO(OH)₂Fe

colorless gas with garlic odor

SO₃^2- + 6M H₂SO₄ = SO₂↑

Acidic; blue to red

SO₃^2- + 6M H₂SO₄ + blue litmus paper

Violet color of KMnO₄ decolorized

SO₃^2- + KMnO₄ + H₂SO₄ = H₂S₂O₆

green bordered flame

BO₃^3- + H₂SO₄, CH₃OH = (CH₃)₃BO₃

brownish red, greenish black

BO₃^3- + Turmeric paper

red to blue violet

BO₃^3- + H₂SO₄ + Carminic acid

white ppt

C₂O₄^-2 + CaCl₂ = CaC₂O₄

insoluble

C₂O₄^-2 + CH₃COOH = —

white ppt

CO₃^2- + Ca(OH)₂ = CaCO₃

no ppt

HCO₃^- + Ca(OH)₂ = —

effervescence

CO₃^2- + H₂SO₄ = CO₂↑

Dark pink/Red

CO₃^2- + H₂SO_{4 + Phenolphthalein}

Light Pink

HCO₃^- + H₂SO_{4 + Phenolphthalein}

Silver Mirror

Tollen’s test: C₄H₄O₆^2- + AgNO₃ + NH₄OH + heat = Ag⁰

Silver Mirror

Tollen’s Test: C₆H₅O₇^3- + AgNO₃ + NH₄OH + heat = Ag⁰

Emerald Green

Denigen’s Test: C₄H₄O₆^2-

Carmine Red

Denigen’s Test: C₆H₅O₇^3-

white crystalline ppt

PO₄^3- + NH₄Cl.NH₄OH + Magnesia Mixture = MgNH₄PO₄

white crystalline ppt

AsO₄^3- + NH₄Cl.NH₄OH + Magnesia Mixture = MgNH₄AsO₄

no ppt

AsO₃^3- + NH₄Cl.NH₄OH + Magnesia Mixture = —

yellow crystalline ppt

PO₄^3- + HNO₃ + (NH₄)₂MoO₄ = (NH₄)₃PO₄ . 12MoO₃

yellow crystalline ppt

AsO₄^3- + HNO₃ = (NH₄)₂MoO₄ = (NH₄)₃AsO₄ . 12MoO₃

no ppt

AsO₃^3- + HNO₃ = (NH₄)₂MoO₄ = —

yellow ppt

CrO₄^2- + Pb(CH₃COO)₂ = PbCrO₄

yellow solution

CrO₄^2- + Pb(CH₃COO)_{2 + NaOH} = Na₂PbO₂

blue ethereal layer

Perchromic acid/ Vanishing blue test: CrO₄^2- + H₂SO₄ + Na₂O₂ + Ether = CrO₅ or H₇CrO₁₀

colorless gas garlic odor + yellow ppt

S₂O₃²^- + 6M H₂SO₄ = SO₂↑ & S

KMnO₄, decolorized

S₂O₃²^- + KMnO₄ + H₂SO₄ = Zn dust (RA)

Red

NO^3- + Zn dust + Sulfanilic acid + Naphthylamine = NO₂^-

brown ring at the interface

NO₃^- + FeSO₄ + conc. H₂SO₄ = FeNOSO₄, [Fe(NO)]⁺²

white ppt

ClO₃^- + AgNO₃ + KNO₂ = AgCl

white ppt

SO₄^-2 + Pb(CH₃COO)₂ = PbSO₄

soluble

SO₄^-2 + Pb(CH₃COO)₂ + CH₃COONH₄ (hot) = Pb(CH₃COO)₂

white etch

F^- + Etch Test (Glass) = SiF₄