Sciencemadness Discussion Board - Copper Acetate

Copper Acetate

Jackson - 12-9-2018 at 09:18

I was wondering about what the exact reaction is to form copper acetate?

Ive heard that you should just add coppper to vinegar but it takes a long time. Ive also heard that if you add hydrogen peroxide it speeds it up.
Is the reaction with the copper, hydrogen peroxide, and vinegar as follows:

Cu + H2O2 —> CuO + H2O

CuO + 2C2H4O2 —> Cu(C2H3O2)2 + H2O

Or does the Hydrogen peroxide react with the acetic acid to form peracetic acid and that reacts more quickly with the copper than normal acetic acid?

I was also wondering if there is any difference between basic copper acetate and copper acetate.

W.R.Monger - 12-9-2018 at 09:42

Yep, copper oxide -> acetate

I would think that you could first torch the shit out of the copper instead of using h202, but that would probably just be more effort.

Also... Referenceless threads in the beginnings section

Xrpdguy - 12-9-2018 at 12:13

Quote: Originally posted by Jackson

I was wondering about what the exact reaction is to form copper acetate?

Ive heard that you should just add coppper to vinegar but it takes a long time. Ive also heard that if you add hydrogen peroxide it speeds it up.
Is the reaction with the copper, hydrogen peroxide, and vinegar as follows:

Cu + H2O2 —> CuO + H2O

CuO + 2C2H4O2 —> Cu(C2H3O2)2 + H2O

Or does the Hydrogen peroxide react with the acetic acid to form peracetic acid and that reacts more quickly with the copper than normal acetic acid?

I was also wondering if there is any difference between basic copper acetate and copper acetate.

You don't need to use copper oxide and reaction with vinegar. You can try to use concentrated acetic acid (it's about 80%) and hydrogen peroxide (3%). That mixture can easily dissolve metal copper.

clearly_not_atara - 12-9-2018 at 12:19

A lot of reactions occur. Peracetic acid is likely present in some small concentration but the more important reaction is the cycle:

H₂O₂ + 2Cu⁺ >> 2Cu²⁺ + 2 OH^- (all molecules in solution)

Cu²⁺ (aq) + Cu (s) >> 2 Cu⁺ (aq)

Acetic acid mostly serves to stabilize the Cu+ and Cu2+ ions and keep them in solution. When peroxide is absent, Cu+ is instead oxidized by atmospheric oxygen, but this process is very slow.

[Edited on 12-9-2018 by clearly_not_atara]

AJKOER - 12-9-2018 at 12:52

Actually, the reaction of Cu (even a solid piece) / HAc (dilute vinegar is great) / 3% H2O2 (or pump in air) is electrochemical in nature, so add so NaCl (especially sea salt is a good electrolyte). Jump start (to avoid the inception period) in a microwave for a minute or so.

Once started, the vigor of the reaction is quite surprising given how weak (and cheap) the reagents employed are!

You may find some of underlying reactions different from your expectations (see, for example, my comments and references at http://www.sciencemadness.org/talk/viewthread.php?tid=81800#... ).

[Edited on 12-9-2018 by AJKOER]

DraconicAcid - 12-9-2018 at 21:48

Quote: Originally posted by clearly_not_atara

A lot of reactions occur. Peracetic acid is likely present in some small concentration but the more important reaction is the cycle:

H₂O₂ + 2Cu⁺ >> 2Cu²⁺ + 2 OH^- (all molecules in solution)

Cu²⁺ (aq) + Cu (s) >> 2 Cu⁺ (aq)

Acetic acid mostly serves to stabilize the Cu+ and Cu2+ ions and keep them in solution. When peroxide is absent, Cu+ is instead oxidized by atmospheric oxygen, but this process is very slow.

Copper(II) will not react with copper metal to give copper(I) unless a ligand is present that will stabilize copper(I) (such as chloride). Acetate isn't much of a ligand.

2 HC2H3O2(aq) + H2O2(aq) + Cu(s) --> Cu(C2H3O2)2(aq) + 2 H2O(l)

AJKOER's suggestion of adding sodium chloride will speed up the reaction, not because it is an electrolyte, but because the chloride will stabilize copper(I) ions in solution.

AJKOER - 14-9-2018 at 04:16

Quote: Originally posted by DraconicAcid

......
AJKOER's suggestion of adding sodium chloride will speed up the reaction, not because it is an electrolyte, but because the chloride will stabilize copper(I) ions in solution.

To state that NaCl is not acting ALSO as an electrolyte is patently incorrect as it implies that there is not a fundamental underlying electrochemical nature to the reaction (see Equation (32) below, which parallels the electrochemical action of oxygen on acidified ferrous leading to ferric).

But, to anyone who has performed the reaction, there is electrochemistry afoot given the obvious inception period (which can be avoided by apparently jump starting the reaction in a microwave). The latter implies electrochemistry and benefits associated with a good starting electrolyte (like NaCl or in cases where the chloride salt is not soluble, as for example, in the system Ag/H2O2/HAc in which NaCl does not work, as AgCl is insoluble, where I have used KNO3).

Another more subtle clue as to the electrochemistry is that the reaction proceeds with very dilute reagents (like 5% acetic acid or vinegar, 3% H2O2 and a bit of KNO3 do just fine in attacking silver metal forming a suspension of silver acetate which dissolves in excess vinegar, providing a gateway soluble silver salt). Also for example, iron will commence to rust in the presence of oxygen, water, an electrolyte, and an acid source, like CO2, even if very dilute. But the standard chemical reaction of HCl acting on iron, apparently proceeds (or not) markedly according to the concentration of the hydrochloric acid.
--------------------------------------

Did find a copy of a source paper, the reaction of interest Equation (32), on p. 129, to quote:

" 4 Cu+ + 4 H+ + O2 → 4 Cu2+ + 2 H2O (32)"

in 'Review of iron-free Fenton-like systems for activating H2O2 in advanced oxidation processes', by Alok D. Bokare and Wonyong Choi, published in Journal of Hazardous Materials, 275:121, May 2014, DOI: 10.1016/j.jhazmat.2014.04.054 .

File attached is from an old downloaded performed last year.

Attachment: Review-of-iron-free-Fenton-like-systems-for-activating-H2O2-in-advanced-oxidation-processes.pdf (3.2MB)
This file has been downloaded 929 times

[Edited on 14-9-2018 by AJKOER]

Abromination - 17-9-2018 at 20:36

Paracetic acid would really only be formed if you used a strong acid to catalyze the reaction between the CH3COOH and the H2O2. A small amount would be formed but would be negligible in te reaction. Check out my method on this doc here.
https://docs.google.com/document/u/1/d/1AoI2VA5L4bmFw2HwXS2O...

Thought I would share this meme I found while I was at it. Not a fan of them but this made me happy. I like how he didn't comment on the periodic table in the background.

[Edited on 18-9-18 by Abromination]