What is the color of Fe3+ ions?

Question

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Answer 1

Lancenigo di Villorba (TV), Italy

You are interested to ferric or Fe(III) compounds.
Someone preceed me she wrote you that "Fe2+ are brown".
Sorry, I would start with this affermation :
Fe++ compounds (e.g. also known like compounds of Fe(II) or ferrous compounds) give aqueous solutions green coloured, characterized by a very weak hue.
Well, now I write you about Fe(III).
I know that the most commons Fe(III) compounds (e.g., among the soluble salts are nitrate, sulphate) show crystalline form, they are white or very weak coloured and they exibit good solubility in water.
As you know, in the case which salt's containt of their solutions is greater than a threshold value (e.g. too many amount of salt in water) these compounds can react with same water : the solution turns brown and you find Fe(III) hydroxide as gel (e.g. jelly) precipitated at the bottom of your vessel. How much is this threshlod of salt containt? This threshold is mainly function of the alkaly's containt of solution (T and P above pH, hence ionic strenght, etc.) by means of an inverse relationship.
Nowadays, speaking about Fe(III) aqueous preparates, it is known that ferric ions are "solvatated" by several molecules of water : so, they are created "secondary chemical bonds" between ions and solvent, it is obvious! But, surprise, this bonds interact with visible spectrum of light and they attribute a yellowish colour to the solution. I think that these bonds are not strong, since this coloration characterize Fe(III) ions, but, generally, its hue is weak, thus it constitutes not a valuable method to detect them.

I hope this helps you.

Answer 2

I am afraid the Fe2+ ions is green but not the Fe3+ ions. I remember that it is between yellow and brown.

Answer 3

hmm..its might be Green..verys similar to the color of clay

Answer 4

green. Fe2+ is brown