Knowledge Vault · Inorganic
Colour of Compounds
Comprehensive colour reference for inorganic compounds, ions, precipitates, complexes, flame tests, borax bead tests, and qualitative analysis observations.
🎨 Colour of Compounds
168 compounds grouped by colour.
White
52Pb(OH)₂·2PbCO₃
ZnCO₃·3Zn(OH)₂
Mg(OH)₂·4MgCO₃·6H₂O
Ag₂SO₃
AgNO₂ — White (crystalline)
CH₃CO₂Ag
HCO₂Ag
Ag₂C₂O₄
Hg₂Cl₂
CaC₂O₄
SrC₂O₄
BaC₂O₄
(HCO₂)₂Hg
AgCl
PbCl₂
PbBr₂
CuI
BaHPO₄
Mg(NH₄)PO₄
CaCO₃
SrCO₃
BaCO₃
AgCN
Pb(CN)₂
Cu(CN)
Cd(CN)₂
Zn₃[Fe(CN)₆]₂
K₂Fe[Fe(CN)₆]
Pb₃(PO₄)₂
Hg₂HPO₄
AlPO₄
Zn₃(PO₄)₂
Ba₃(PO₄)₂
Mg(OH)₂
K₂Ca[Fe(CN)₆]
KHC₄H₄O₆
(NH₄)HC₄H₄O₆
KClO₄
Zn[Hg(SCN)₄]
CuSCN
CuSO₄·H₂O — Bluish white
Ag₂S₂O₃
PbS₂O₃
HgS₂O₃
Bi₂(S₂O₃)₃
Cu₂S₂O₃
BaSO₄
PbSO₄
ZnS
Al(OH)₃
Zn(OH)₂
Mn(OH)₂
Yellow
27CdS
AgI
PbI₂
AgBr — Pale yellow
Ag₃PO₄
HgSO₄·2HgO
SrCrO₄
BaCrO₄
PbCrO₄
K₂CrO₄ (CrO₄²⁻)
FePO₄
K₃[Co(NO₂)₆]
(NH₄)₃[Co(NO₂)₆]
K₂[PtCl₆]
(NH₄)₂[PtCl₆]
KZn[Co(CN)₆]
Cu(CN)₂
(NH₄)₃[P(Mo₃O₁₀)₄] — Canary yellow
Bi(C₆H₃O₃) (bismuth pyrogallate)
Fluorescein
PbO (Massicot)
ZnO (hot)
Ag₂CO₃ — Very light yellow
Hg₂CO₃
As₂S₃
As₂S₅
SnS₂
Black
16Ag₂S
PbS
FeS
NiS
CoS
MnO(OH)₂
Hg (free metal)
Cu(SCN)₂
CuO
Ag₂O — Brownish black
BiI₃ — Brownish black
HgS
Hg + HgS
CuS
Cu₂S
Bi₂S₃ — Brownish black
Brown
11HgO·Hg(NH₂)I — Brown
Fe(CN)₂ — Yellowish brown
Fe(CN)₃ — Reddish brown
Ag₂Cr₂O₇ — Reddish brown
Cu₂[Fe(CN)₆] — Chocolate brown
Fe[Fe(CN)₆] — Brown colouration
KI₃ — Dark brown
[Co(NH₃)₆]²⁺ (solution) — Brownish yellow
SnS — Brown
HgCO₃·3HgO — Reddish brown
Fe(OH)₃ — Reddish brown
Red
15Fe(SCN)₃ — Blood red
Fe(OH)₂(CH₃CO₂)
Fe(OH)₂(HCO₂)
[Mn(C₂O₄)₃]³⁻ — Red colouration
Ag₂CrO₄ — Brick red
Hg₂CrO₄ — Brick red
CrO₃ — Dark red (crystals)
HgI₂ — Scarlet red
Eosin (tetrabromofluorescein)
Ni(DMG)₂ — Rosy red
[Fe(dipy)₃]²⁺ — Red colouration
[Fe(C₁₂H₈N₂)₃]²⁺ — Red colouration
PbO (Litharge)
Cu₂O — Brick red
Tetrachromate (Cr₄O₁₃²⁻) — Dark red
Pink
6CoCl₂·6H₂O
CoCl₂·4H₂O
Co(OH)₂
[Co(NH₃)₆]³⁺ (solution)
Mn₃(PO₄)₂
MnS — Buff / flesh
Orange
4K₂Cr₂O₇ (Cr₂O₇²⁻)
Trichromate (Cr₃O₁₀²⁻) — Orange-red
[BiI₄]⁻ (solution) — Orange to yellow
Sb₂S₃
Green
11Cu(OH)₂·CuCO₃
Hg₂I₂
[Cr(OH)₄]⁻ (solution)
Cu₃[Fe(CN)₆]₂
CoO·ZnO / Co[ZnO₂] (Rinmann's green)
Cr₂O₃
FeSO₄·7H₂O (green vitriol)
Cr(OH)₃
Fe(OH)₂ — Dirty green
Ni(OH)₂
Cl₂ (gas) — Greenish yellow
Blue
8I₂ + starch — Deep blue
CuSO₄·5H₂O (blue vitriol)
CoCl₂ (anhydrous)
[Ni(NH₃)₆]²⁺ (solution) — Deep blue
Fe₄[Fe(CN)₆]₃ (Prussian blue)
Fe₃[Fe(CN)₆]₂ (Turnbull's blue)
Cu(OH)₂
[Cu(NH₃)₄]²⁺ (solution) — Deep blue
Violet
4[Ni(en)₃]S₂O₃ — Violet
Cu[Hg(SCN)₄]·Zn[Hg(SCN)₄] — Violet
CoCl₂·2H₂O — Red violet
MnO₄⁻ — Intense purple
Grey
1Hg + HgO
Colourless
13[HgS₂]²⁻ — Colourless
[PbI₄]²⁻ — Colourless
[HgI₄]²⁻ — Colourless
[Ag(CN)₂]⁻ — Colourless
[Cd(CN)₄]²⁻ — Colourless
[Cu(CN)₄]³⁻ — Colourless
[Cu(SCN)₄]³⁻ — Colourless
[FeF₆]³⁻ — Colourless
[Ag(S₂O₃)₂]³⁻ — Colourless
[Pb(S₂O₃)₂]²⁻ — Colourless
[Hg(S₂O₃)₂]²⁻ — Colourless
[Bi(S₂O₃)₃]³⁻ — Colourless
[Cu₆(S₂O₃)₅]⁴⁻ — Colourless
⚗️ Colours of Some of the First Row (Aquated) Transition Metal Ions
Aqueous ion colours — a separate quick-reference for the 3d series.
| Ion | Colour | |
|---|---|---|
| Sc³⁺ | Colourless | |
| Ti⁴⁺ | Colourless | |
| Ti³⁺ | Purple | |
| V⁴⁺ | Blue | |
| V³⁺ | Green | |
| V²⁺ | Violet | |
| Cr³⁺ | Violet | |
| Mn³⁺ | Violet | |
| Cr²⁺ | Blue | |
| Mn²⁺ | Pink | |
| Fe³⁺ | Yellow | |
| Fe²⁺ | Green | |
| Co³⁺ / Co²⁺ | Blue-Pink | |
| Ni²⁺ | Green | |
| Cu²⁺ | Blue | |
| Zn²⁺ | Colourless |
🧪 Ion Colors (aqueous + hydroxide ppt)
Cu²⁺ — Blue
Cu(OH)₂ — blue ppt
Fe²⁺ — Pale green
Fe(OH)₂ — dirty green ppt
Fe³⁺ — Yellow / brown
Fe(OH)₃ — reddish-brown ppt
Ni²⁺ — Green
Ni(OH)₂ — green ppt
Co²⁺ — Pink
Co(OH)₂ — blue/pink ppt
Mn²⁺ — Pale pink
Mn(OH)₂ — white→brown ppt
Cr³⁺ — Green / violet
Cr(OH)₃ — green ppt
MnO₄⁻ — Intense purple
Cr₂O₇²⁻ — Orange
CrO₄²⁻ — Yellow
Cu²⁺ + NH₃ (excess) — Deep blue [Cu(NH₃)₄]²⁺
⚪ Carbonate Precipitates (with (NH₄)₂CO₃ / Na₂CO₃)
| Reagent | Precipitate | Colour |
|---|---|---|
| CaCl₂ | CaCO₃ | White |
| SrCl₂ | SrCO₃ | White |
| BaCl₂ | BaCO₃ | White |
| AgNO₃ | Ag₂CO₃ | White (very light yellow) |
| Hg₂(NO₃)₂ | Hg₂CO₃ | Yellow |
| HgCl₂ | HgCO₃·3HgO | Reddish brown |
| ZnCl₂ | ZnCO₃·3Zn(OH)₂ | White |
| Pb(OAc)₂ | Pb(OH)₂·2PbCO₃ | White |
| MgCl₂ | Mg(OH)₂·4MgCO₃·6H₂O | White |
| CuCl₂ | Cu(OH)₂·CuCO₃ | Green |
⚫ Group II — Thiosulfate (white) → Sulfide (black)
| Ion (reagent) | White ppt (S₂O₃²⁻) | Black ppt (S²⁻) | Clear solution |
|---|---|---|---|
| Ag⁺ (AgNO₃) | Ag₂S₂O₃↓ | Ag₂S↓ | [Ag(S₂O₃)₂]³⁻ |
| Pb²⁺ (Pb(OAc)₂) | PbS₂O₃↓ | PbS↓ | [Pb(S₂O₃)₂]²⁻ |
| Hg²⁺ (Hg(NO₃)₂) | HgS₂O₃↓ | HgS↓ | [Hg(S₂O₃)₂]²⁻ |
| Bi³⁺ (BiCl₃) | Bi₂(S₂O₃)₃↓ | Bi₂S₃↓ | [Bi(S₂O₃)₃]³⁻ |
| Cu²⁺ (CuSO₄) | Cu₂S₂O₃↓ | Cu₂S↓ | [Cu₆(S₂O₃)₅]⁴⁻ |
🔥 Flame Test Colors
Na — Golden yellow
K — Lilac / violet
Li — Crimson red
Ca — Brick red
Sr — Crimson / scarlet
Ba — Apple / pale green
Cu — Blue-green
Cs — Blue / violet
🧫 Sublimate → H₂S Precipitate Colours
| Sublimate salt | Precipitate | Colour |
|---|---|---|
| HgCl₂ | HgS | Black |
| Hg₂Cl₂ | Hg + HgS | Black |
| As₂O₃ | As₂S₃ | Yellow |
| Sb₂O₃ | Sb₂S₃ | Orange |
🔵 Borax Bead Colours
| Metal | Oxidising · hot | Oxidising · cold | Reducing · hot | Reducing · cold |
|---|---|---|---|---|
| Cr | Yellow | Green | Green | Green |
| Mn | Violet | Violet | Colourless | Colourless |
| Fe | Yellowish brown | Yellow | Green | Green |
| Co | Blue | Blue | Blue | Blue |
| Ni | Violet | Reddish brown | Grey | Grey |
| Cu | Green | Blue | Colourless | Opaque (red Cu) |
Na₂CO₃ bead: green bead → Mn compound · yellow bead → Cr compound. Borax bead test is done only for coloured salts.