Chemistry Colour of Fe3+

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The discussion centers on the reaction of the Fe2+ complex with Cl2, leading to the oxidation of iron and the formation of the Fe3+ complex. The equation proposed is 2Fe(H2O)(6)^2+ + Cl2 -> 2Cl- + 2Fe(H2O)(6)^3+. There is confusion regarding the color of the Fe3+ ion in water, with claims that it appears yellow, yet the exam question describes it as brown. The difference in color perception is attributed to variations in intensity, and it is suggested that discussing colors should be replaced with a focus on spectral properties for clarity. The conversation highlights the complexities and nuances in understanding the chemistry of iron complexes.
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I've been tasked with writing an equation to show the reaction of the Fe2+ complex with Cl2. I believe that the oxidation state of the Iron has changed, so I would write 2Fe(H2O)(6)^2+ + Cl2 -> 2Cl- + 2Fe(H20)(6)^3+, but I can't be sure this is correct.

Is the 2Fe(H20)(6)^3 ion not yellow in water due to the formation of its conjugate base? If so, is there any hint in the question as to why it should appear brown? THANK YOU!!
 
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sdfsfasdfasf said:
2Fe(H2O)(6)^2+ + Cl2 -> 2Cl- + 2Fe(H20)(6)^3+

General idea is OK, whether some H2O molecules are not replaced with Cl-, producing a bit different complex, is another question.

sdfsfasdfasf said:
Is the 2Fe(H20)(6)^3 ion not yellow in water due to the formation of its conjugate base?

It is yellowish/brown even in low pH solutions, where the conjugate base is not present.
 
It's just strange because my textbook (from which this exam question is based off) claims that hydrated Fe3+ is yellow, and all other exam questions on this topic use that piece of information, its just this one that says its brown.
 
Difference between yellow and brown is mostly just intensity, these are not completely different colors. Especially when you take into account that these names of colors are very handwavy, there is no rigor behind. The only way to treat these things seriously is to talk not about "colors" but about spectra.
 
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