Crust on old Battery -- What happens when you drop Vinegar on it?

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Discussion Overview

The discussion revolves around the chemical reactions occurring when vinegar is applied to an old battery with a whitish encrustation. Participants explore the nature of the encrustation, hypothesize about its composition, and discuss the potential by-products of the reaction between vinegar (acetic acid) and the crust, which may contain alkaline substances.

Discussion Character

  • Exploratory
  • Chemical reasoning
  • Debate/contested

Main Points Raised

  • One participant observed vigorous fizzing and disappearance of the encrustation upon applying vinegar, suggesting a chemical reaction.
  • Another participant proposed that the encrustation could be potassium carbonate, formed from potassium hydroxide in the battery reacting with atmospheric CO2.
  • There is a suggestion that the reaction between acetic acid and the carbonate would produce water and carbon dioxide, although the exact nature of the reaction is debated.
  • Concerns were raised about the implications of the composition of acetic acid and whether it would decompose during the reaction.
  • Questions were posed regarding the fate of potassium during the reaction, with speculation that it could convert to potassium acetate or be washed away.

Areas of Agreement / Disagreement

Participants express differing views on the chemical processes involved, particularly regarding the decomposition of acetic acid and the fate of potassium. No consensus is reached on these points.

Contextual Notes

Participants rely on assumptions about the chemical composition of the encrustation and the reactions involved, which may not be fully substantiated. The discussion includes uncertainties about the behavior of potassium and the specifics of the reaction products.

Mikestone
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I had an old Duracell battery with the bottom covered by a whitish encrustation. When I dropped some vinegar on this, there was a vigorous fizzing, and the encrustation disappeared.

Any idea what the encrustation was (presumably soething alkaline, since vinegar is acidic) and what the likely by-products were?
 
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A quick Google 'crust on battery' suggests some likely candidates. Why don't you kick start the discussion with some initial facts?
 
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Thanks for the suggestion.

I've seen online that the crust may well be potasssium carbonate. I've also checked and found that acetic acid is an elaborate combination of hydrogen carbon and oxygen.

This being so I should guess that the main products would be water and carbon dioxide. Only thing I'm unsure about is what happens to the potassium Might it just get deposited aon the bottom of the battery, or would it combine with something?
 
Mikestone said:
I've seen online that the crust may well be potasssium carbonate.

Quite likely. Batteries contain concentrated KOH as an electrolyte, if it leaks it absorbs atmospheric CO2 producing carbonate.

I've also checked and found that acetic acid is an elaborate combination of hydrogen carbon and oxygen.

Beware: just because it is a combination of these elements doesn't mean it will decompose during the reaction to produce water and carbon dioxide, which you seem to be suggesting:

This being so I should guess that the main products would be water and carbon dioxide.

Yes, but it has nothing to do with the composition of acetic acid. Actually the important part here is not the "acetic", but "acid". Any acid reacting with any carbonate will produce water and carbon dioxide.

Only thing I'm unsure about is what happens to the potassium Might it just get deposited aon the bottom of the battery, or would it combine with something?

Potassium is all the time there, just converted to potassium acetate. Could be it was washed away with the acetic acid (I suppose you used a vinegar, which is a diluted solution of the acid).
 

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