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24 AUG 2004: General Chemistry

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Donaldson Tan:
Suggest an explanation for the appearance of a blue precipitate when ethanoic acid is added slowly to a deep dark blue solution.

Mitch:
ppt?

Donaldson Tan:

--- Quote from: Mitch on August 24, 2004, 11:48:42 PM ---ppt?

--- End quote ---

ppt is abbreviation for 'precipitate' - something that I was taught in school

Mitch:
Oh, I was thinking parts per trillion.

Limpet Chicken:
Dark blue suggests to me, either copper aspirinate, hydrated copper (II) sulfate, or a tetrammine copper (II) complex salt.
 
Maybe dry hydrated copper (II) sulfate, and acetylsalicylic acid mixed, then acetic acid (aq) added to form dark blue copper aspirinate while liberating H2SO4.

Tetrammine copper solution+an alkali chlorate/perchlorate salt+H2O2-->tetramminecopper (II) perchlorate  on addition of acid to liberate chloric/perchloric acid (dilute) from the chlorate/perchlorate?

In my experience, I have prepared tetramminecopper (II) perchlorate, and the way I prepared it, it crystallises as a dark turquoise-to-blue precipitate that deflagrates slowly when ignited, roughly as fast as a drop of glycerine on powdered KMnO4 ( I have heard that the chlorate is a friction sensitive primary)

I only have experience with the perchlorate, and it looked like you described, however, I think the product was at least slightly impure, hmm, I think I will start a thread on tetrammine complexes when I'm slightly less stoned, and have sufficient inclination LOL ;D

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