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

[Mikestone]

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?

 

[DaveC426913]

A quick Google 'crust on battery' suggests some likely candidates. Why don't you kick start the discussion with some initial facts?

 

[Mikestone]

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?

 

[Borek]

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).