Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: thedoc on 08/04/2013 18:30:03

Title: Is a potato used as a battery still edible?
Post by: thedoc on 08/04/2013 18:30:03
Andrew Blair  asked the Naked Scientists:
   
I can make a battery out of a potato to power a clock. What does this do to its edibility once the energy has been all used up? Is it safe to eat and will it taste any better or be bad for me in any way?

Cheers,

Andrew Blair

Squamish, BC
Canada

What do you think?
Title: Re: Is a potato used as a battery still edible?
Post by: Ethos_ on 08/04/2013 19:18:06
Andrew Blair  asked the Naked Scientists:
   
I can make a battery out of a potato to power a clock. What does this do to its edibility once the energy has been all used up? Is it safe to eat and will it taste any better or be bad for me in any way?

Cheers,

Andrew Blair

Squamish, BC
Canada

What do you think?
Not sure how it will taste, but it will reduce the ascorbic acid content. Potatoes have a higher content of vitamin C than even oranges do.
Title: Re: Is a potato used as a battery still edible?
Post by: CliffordK on 08/04/2013 20:16:35
You will also get some metal ions in your potato.
Copper ions, zinc ions, etc, depending on what your electrodes are.
Perhaps some organometallic compounds.

While a potato resists spoilage reasonably well, the electrodes may also provide a site of entry for microbes.

Some of the metal ions may in fact be vitamins, but you would have to look up what you are using as electrodes.

Personally, I would at least cut around the electrodes and remove any suspicious looking material, then thoroughly cook and eat it.
Title: Re: Is a potato used as a battery still edible?
Post by: majorminor on 09/04/2013 17:27:17
Make sure you remove all metal from your battery potato before eating or you could chip a tooth.

 :I
Title: Re: Is a potato used as a battery still edible?
Post by: Bored chemist on 09/04/2013 19:43:31
This thread seems to be essentially all wrong.
"What does this do to its edibility once the energy has been all used up? "
The energy used to run the clock doesn't came from the potato. It comes from the coal used to smelt the zinc from its ore.
"Not sure how it will taste, but it will reduce the ascorbic acid content."
Probably true, but not a big deal
"Potatoes have a higher content of vitamin C than even oranges do."
Not true
http://en.wikipedia.org/wiki/Vitamin_C#Plant_sources

"You will also get some metal ions in your potato.
Copper ions, zinc ions, etc, depending on what your electrodes are."
Not quite true, there's no "probably" about it. The energy is released by the conversion of metallic zinc to zinc ions.

"Perhaps some organometallic compounds."
I doubt it; most organozinc compounds are not stable in the presence of air or water.

"Some of the metal ions may in fact be vitamins"
No, they may be minerals which the body uses, but they can't be vitamins since ther are not organic compounds.


Nobody has mentioned the fact that spuds exposed to light generate toxic chemicals
http://en.wikipedia.org/wiki/Solanine#Solanine_in_potatoes

The simple answer is no. Throw the used potato away.
Title: Re: Is a potato used as a battery still edible?
Post by: Ethos_ on 09/04/2013 21:05:11

"Potatoes have a higher content of vitamin C than even oranges do."
Not true
http://en.wikipedia.org/wiki/Vitamin_C#Plant_sources

I stand corrected BC, more evidence that one should always check before repeating something they only heard from someone they trusted.
Title: Re: Is a potato used as a battery still edible?
Post by: Andrew Blair on 10/04/2013 19:39:32
@Bored Chemist
Quote
The energy used to run the clock doesn't came from the potato. It comes from the coal used to smelt the zinc from its ore.

I always assumed that there was something in the potato itself that gets used up like with a chemical battery. Would you please elaborate on your point about coal?

Title: Re: Is a potato used as a battery still edible?
Post by: Bored chemist on 12/04/2013 16:21:59
They dig zinc oxide out of the ground
The add coal and heat it to get zinc
2 ZnO + C  --> 2 Zn + CO2
If they just burned that coal they would get energy.
This way some of that energy is "stored" by making metallic zinc.
When the zinc is oxidised that energy is released.