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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: unknown_analysis on January 24, 2011, 08:54:56 AM

Title: What is FeCl3 + HCl --> ?
Post by: unknown_analysis on January 24, 2011, 08:54:56 AM

How come the yellow solution, FeCl₃, becomes colorless when mixed with HCl? The molar concentration of FeCl₃ is 0.05 M and HCl is 0.075 M. What is FeCl₃ + HCl --> ? I'm just confused.
I am guessing that the acidity of the solution affects the color of FeCl₃? Can anyone help me?

_{Imma give you mole snaaaackks! LOL. ;D}
Thanks.

Cheers. :D

Title: Re: What is FeCl3 + HCl --> ?
Post by: DevaDevil on January 24, 2011, 10:27:33 AM

I know that a complex of iron can be formed: FeCl₄^- when iron chloride is in the presence of excess chloride, but this should have a light yellow color as well.

Title: Re: What is FeCl3 + HCl --> ?
Post by: AWK on January 25, 2011, 03:03:54 AM

Water solutions of FeCl3 are brown-yellow because of hydrolysis
Fe(H₂O)₆³⁺ + H₂O = FeOH(H₂O)₅²⁺ + H₃O⁺
Addition of any strong acid moves this equilibrium to the left. Only at high concentration of HCl tetrachloroferric acid is formed in small amounts though it can be isolated as etherate (C₂H₅OC₂H₅)in anhydrous conditions.