Colour Of Substances

(A) Colour of Substances The several possibilities for a particular colour are given below: Colour of Unknown Chemicals/Ions Substances Copper(II) oxide, CuO Iron(II) oxide, FeO Black Manganese(IV) oxide, MnO2 Iodine crystals, I2

Colour of Unknown Chemicals/Ions Substances Examples: Hydrated copper(II) sulfate crystals, CuSO4.5H2O Aqueous copper(II) sulfate solution, CuSO4(aq) Blue Copper(II), Cu2+ Hydrated copper(II) nitrate crystals, Cu(NO3)2.3H2O Aqueous copper(II) nitrate solution, Cu(NO3)2(aq) Anhydrous cobalt(II) chloride, CoCl2

Colour of Unknown Chemicals/Ions Substances I2 (solution) Brown Lead(IV) oxide, PbO2 Examples: Hydrated iron(III) nitrate crystals, Fe(NO3)3.9H2O Iron(III), Fe3+ Aqueous iron(III) nitrate solution, Reddish-brown Fe(NO3)3(aq) Iron(III) oxide, Fe2O3 Copper metal

Colour of Unknown Chemicals/Ions Substances Examples: Hydrated iron(II) sulfate crystals, FeSO4.7H2O Iron(II), Fe2+ Green / Light Green Aqueous iron(II) sulfate solution, FeSO4(aq) Examples: Copper(II) carbonate, CuCO3 Copper(II), Cu2+ Hydrated copper(II) chloride crystals, CuCl2.2H2O Potassium Purple manganate(VII), KMnO4 Potassium Orange dichromate(VI), K2Cr2O7

Colour of Unknown Chemicals/Ions Substances Lead(II) Yellow oxide, PbO Lead(II) iodide, PbI2, See the web site below for the test for iodide http://www.youtube.com/watch?v=tQ_sJTQAnRM Silver bromide, AgBr (Pale yellow) Silver iodide, AgI

Colour of Unknown Chemicals/Ions Substances Examples: Zinc powder Metals (in Grey powder form) Aluminium powder Iron powder Co2+ Hydrated cobalt(II) Pink (hydrated) chloride crystals, CoCl2.6H2O Aqueous cobalt(II) chloride solution, CoCl2(aq)

Colour of Unknown Chemicals/Ions Substances Na+, K+, NH4+, Ca2+, Zn2+, Pb2+, Al3+ White (Absence of salts like iron(II), iron(III), copper(II) and other transition elements) Colourless Dilute acids, alkalis, hydrogen peroxide(H2O2) Solution (B) Action of Heat on Carbonates Cation Observations/Gas Equation evolved Na+ White residue; Na2CO3.10H2O(s) → Na2CO3(s) + 10H2O(g) Water vapour evolved white crystals white powder + K White residue Not decomposed Ca 2+ White residue; carbon CaCO3(s) → CaO(s) + CO2(g) dioxide evolved white white Zn2+ Residue is yellow when hot ZnCO3(s) → ZnO(s) + CO2(g) and white when cold; white yellow –hot carbon dioxide evolved white - cold Pb 2+ Yellow (orange) residue; PbCO3(s) → PbO(s) + CO2(g) carbon dioxide evolved white yellow Al3+ White residue; carbon Al2(CO3)3(s) → Al2O3(s) + 3CO2(g) dioxide evolved white white Cu 2+ Black residue; carbon CuCO3(s) → CuO(s) + CO2(g) dioxide evolved green black Fe2+ Black residue turning FeCO3(s) → FeO(s) + CO2(g) reddish brown on contact green black with air (oxidation); carbon dioxide evolved 4FeO(s) + O2(g) → 2Fe2O3(s) air reddish-brown Fe3+ Reddish-brown residue; Fe2(CO3)3(s) → Fe2O3(s) + 3CO2(g) carbon dioxide evolve brown reddish-brown

Colour Of Substances

by 4 E5 on Sep 11, 2009

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Colour Of Substances — Document Transcript