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When you burn an acetate what compounds are formed?

  1. Jun 18, 2007 #1
    When you burn an acetate what compounds are formed? Like if you burn copper(II) acteate(CuC4H6O4), because I was making copper acetate and when i was drying it i left it too long and it burned and i redissolved it in water and it was a dark green solution with a reddish orange precipitate in the bottom. How can i dry solutions so they don't burn, besides watching it closely? When i made the copper acetate the solution was saphire blue then when it was dried it was a dark green then in solution of water it is dark green, i have gotten blue crystals before so i think it is the way i am drying it(under a heat lamp). I have many more questions(Why can't i get my iron acetate solution to turn red?) that i have pondered but they can wait for now.
     
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  3. Jun 18, 2007 #2

    chemisttree

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    How did you make the cupric acetate? Cupric acetate (verdigris) is supposed to form green solutions. Cupric subacetate or basic cupric acetate can be blue if the ratio of cupric acetate to cupric hydroxide to water is 1:1:5. Drying this removes the water (and the nice blue color) producing copper acetate (green) and copper hydroxide (greenish blue) or copper oxide (brownish black) with further heating.
     
  4. Jun 18, 2007 #3
    i ran an electric current through a copperpipe(+ end) and a copper wire(-end) in vinegar the negitive end produced a black insoluble compound (flame test produces lime green flame)that accumulated on the wire with no harm to the wire then it falls off and sinks.
     
    Last edited: Jun 18, 2007
  5. Jun 18, 2007 #4

    mrjeffy321

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    What did you use as an electrolyte in this electrolytic cell you used to produce the Cu-Acetate?
     
  6. Jun 18, 2007 #5
    whatever was in the vinegar when i bought it
     
  7. Jun 19, 2007 #6

    mrjeffy321

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    Oh yes, vinegar of course, how silly of me.

    Is the black compound which formed at the cathode soluble in Hydrochloric acid (if you have any available)?
     
  8. Jun 19, 2007 #7
    Not pure but i have toilet cleaner that contains HCl, along with detergents and coloring (blue) it is only 20% HCl. Iron allowed to react with it turns the solution a light yellow. If it was soluble what color would the solution be, assuming you have pure HCl with no coloring? How pure is the muritic acid you get from a hardware store?
     
  9. Jun 19, 2007 #8

    mrjeffy321

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    I think it is probably fair to assume that the black stuff is some type of Copper salt, right, since what other cations are present in the solution....Sodium, but Na will certianly not plate out and I dont think it could be any Sodium salt since those are usually white and will readily dissolve in water.

    If it is a Copper salt, then dissolving it in solution will yeild Cu+2 ions which will form a complex with water molecules turning the solution blue.
    If the solution becomes concentrated enough, it will begin to form complexes with the Chloride ions as well and turn the solution a dark green.

    it might be Copper(II) Oxide, in which case it will be readily soluble in HCl and yeild a blue solution when dillute (forming CuCl2 (aq)).

    The toilet bowl cleaner might work as long as you are able to tell a color change if it occurs.
    The muriatic acid you get at the hardware store is very pure HCl. The stuff I buy is about 37% HCl by weight, the rest being water.
     
  10. Jun 19, 2007 #9
    i don't think that i could tell if a color change occured if the color change is the same as the solution initially unless the color is changed, will iron(III)chloride effect the outcome much if any?
     
  11. Jun 20, 2007 #10

    mrjeffy321

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    No, I dont think that it should.

    If you are referring to the Iron Chloride solution you made by dissolving Iron metal in Hydrochloric acid (and thus turning it a yellow color), that is not Iron(III) Chloride, it is actually Iron(II) Chloride.
    [not that it mattered, just for your personal enjoyment]

    What you might be able to do is somehow bleach the color out of the HCl toilet bowl cleaner so that it is initially colorless.
    Although I do not know what you could use to oxidize the color away with...the two obvious choices which pop into my head (Sodium Hypochlorite [AKA "bleach"] and KMnO4) would not work well since they would oxidize the Chloride ions from the HCl to release Chlorine gas....something you will want to avoid.
    But you might be able to see a color change from dissolving the (what I think to be) Copper salt in the HCl. If nothing else, you could at least tell if the solid dissolved or not.
     
  12. Jun 20, 2007 #11
    I know it is dangerous but could you distill the cleaner to remove coloring ect. and then try to dissolve it (i realise that the boiling point of acids are higher than water)
     
  13. Jun 20, 2007 #12
    I just tryed to dissolve it and it wouldn't dissolve at all but the precipitate from when i burned it is soluble and the solution tuns from blue to green
     
  14. Jun 20, 2007 #13

    mrjeffy321

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    No, you cannot concentrate the HCl in this manner.
    Hydrochloric acid forms an azeotrope with water which will prevent you from getting it beyond about 20%.
    Also, the boiling point of HCl is not always higher than that of pure water. Somewhere around 25% HCl the boiling point dips below 100 degrees C and continues to fall. At 38% HCl, the boiling point of the solution is only about 48 degrees C.
     
  15. Jun 20, 2007 #14
    Could the coloring be some copper compound?
     
  16. Jun 20, 2007 #15
    You can still purify it right?
     
  17. Jun 20, 2007 #16

    mrjeffy321

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    The 'natural' blue color of the HCl is almost certainly some dye the manufacturer put in (to keep people from drinking it).

    It is interesting that the solution turned from blue to green.
    Was it is dark green (on the verge of becoming black) or a pale green?

    If you had the proper equipment, theoretically, I suppose you could purify the HCl by boiling it and condensing the vapors.
    But doing this does not sound like a good idea to me.
     
  18. Jun 23, 2007 #17
    It was the color of nice green grass (dark green) but i didn't add very much, like a pinch. I just got some muratic acid (31.45%) today and it looks like smoke from dry ice when you pour it out(i'm careful)
     
  19. Jun 23, 2007 #18
    the copper compound is a little lumpy, it all turned greenish tourquoise (CuOH i think), and I added some to the muric acid and i let it sit and it turned the solution a yellowish green
     
  20. Jun 24, 2007 #19

    mrjeffy321

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    I will try to recreate your experiment tomorrow and see what results I get.
     
  21. Jun 24, 2007 #20
    copper for both electrodes
    cheap vinegar, white distilled, glutin free, 5%
     
  22. Jun 25, 2007 #21

    NoTime

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    IIRC the muritic acid you get from a hardware store is about 99% pure.
    The last bottle I had stated purity and concentration on the lable.
     
  23. Jun 25, 2007 #22
    the bottle i have just says the concentration not the purity
     
  24. Jun 26, 2007 #23

    mrjeffy321

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    I performed the experiment yesterday.

    For the cathode of the electrolytic cell I used a coiled piece of Copper wire.
    For the anode of the cell, I used a small strip of Copper metal a few mm thick.
    As the electrolyte I used a concentrated solution of Acetic Acid prepared by diluting glacial acetic acid down to about 50% (roughly estimated) by weight.
    I used a current controllable (one with a knob which allows be to adjust the current to whatever I wish [within reason] at about 5 volts) power supply.

    I performed two runs of the cell.
    One run I used a constant current of about 500 mA for about 30 minutes.
    The second run I used a current about 300 mA for a few hours, then I lowered it down to 50 or 100 mA overnight.
    Both runs gave me to the same result (just one was faster than the other).

    The anode corroded and a dark substance formed on the cathode. The electrolyte solution turned the characteristic blue color as one would expect from a Cu+2 (aq) solution. While the cathode was immersed in the blue solution, the substance forming on the cathode looked black, but when one lifts the electrode out of solution the substance looked green. Near the bottom of the cathode, the substance looks a little like Copper metal, it has a similar color and shine even though the actual Copper wire is not exposed at that point.

    The green substance formed on the cathode was not water soluble, nor did it dissolve (or show any signs of a chemical reaction) when it was submerged into concentrated Hydrochloric acid.
    However, a chemical reaction defiantly occurs when the substance is in the presence of concentrated Nitric acid. The substance reacts with Nitric acid to give off brown NO2 gasses and the solution turns blue as the substance dissolved in the acid.


    If I had to guess what the substance formed on the cathode was, I would probably say it is Copper metal. However, the color makes me question that slightly. The color (greenish) does not look anything like Copper metal in the usually sense….but maybe that is just because of the way it is plated onto the surface. Also, I would have thought the HCl would (although it would not have dissolved the Copper) have perhaps cleaned off any Copper Oxide coating on the Cu to give it the usual Cu color if the green color is resulting from any oxidization which has occurred to the Cu, but the HCl seemed to have no effect.

    I remember reading some time ago that one way to purify Copper metal is to electrolytically dissolve it and re-plate it out on to another surface. The Copper metal will be oxidized into solution and then be reduced back out at Cu metal, but the impurities will be left behind in a pile underneath the Copper anode. So this is what I think it occurring, you are basically plating over Copper from one electron to the other.
    The Copper ions which have not yet been plated over are causing the blue color of the electrolyte solution as a aqueous solution of Copper(II) Acetate is forming.

    Here are some pictures…

    Electrodes after the electrolytic reaction:
    http://i62.photobucket.com/albums/h104/mrjeffy321/PF-CopperAcetate/IMG_0611.jpg
    Solution after electrolysis:
    http://i62.photobucket.com/albums/h104/mrjeffy321/PF-CopperAcetate/IMG_0615.jpg
     
  25. Jun 27, 2007 #24
    i saw one time you dissolve Copper oxide in HCl and put an iron nail in it and it will plate it with copper. i tried it and it worked.
    I put 1500mA into it and it formed in 2 days with 5% acetic acid
    How would one go about drying a solution without burning it, besides evaporating at room temp?
     
  26. Jun 27, 2007 #25

    chemisttree

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    Keep the solution below the 'burning' temperature of the compound. What makes you think that you burned the material? Copper acetate can be heated all the way to 240C without risk of burning.
     
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