Making a voltaic pile with Euro coins

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Discussion Overview

The discussion revolves around the feasibility of creating a voltaic pile using Euro coins as electrodes, exploring the materials involved, the effectiveness of different electrolytes, and the principles behind voltaic cells. Participants share their experiences and insights regarding the construction and expected performance of such a device.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant attempted to create a voltaic pile using 1€ and 50c coins but did not measure any voltage, questioning the suitability of the coins based on their metal composition.
  • Another participant suggested that the issue lies not in the coin composition but in the connections and the choice of electrolyte, criticizing sea salt as a poor option for achieving voltage.
  • A different viewpoint proposed that while € coins may not be ideal, the key factor is the contact with the electrolyte rather than the internal composition of the coins.
  • One participant shared a successful experience using graphite and zinc as electrodes in salt water, indicating that immersion in a liquid electrolyte is more effective than using wet paper.
  • Another participant noted that the original voltaic pile utilized brine-soaked cloth, suggesting that ion mobility may not be critical for voltage generation, although it affects current.
  • A question was raised regarding the viability of using brine if one of the reactants is an ion of an electrode metal, prompting a discussion about the Nernst equation and its implications for cell potential.
  • A later reply acknowledged that while a voltaic cell can produce voltage, it may be weak, referencing the Nernst equation for clarification.

Areas of Agreement / Disagreement

Participants express differing opinions on the effectiveness of Euro coins as electrodes and the role of the electrolyte, indicating that multiple competing views remain without a consensus on the best approach.

Contextual Notes

Limitations include the unclear effectiveness of wet paper as an electrolyte compared to liquid solutions, and the dependence on specific metal-ion interactions in the electrolyte for optimal performance.

cnidocyte
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Can it be done? I tried stacking cells made with 1€ coins + 50c coins separated by some tissue soaked in sea salt but didn't measure any voltage with the multimeter.

The problem is every coin except the brown ones consist mainly of copper and the brown ones are steel plated with copper. Heres the composition of Euro coins:

1c, 2c and 5c: Copper plated steel
10c, 20c and 50c: 89% copper, 5% aluminium, 5% zinc, 1% tin
Centre of 1€ and ring of 2€: 75% copper, 25% nickel
Centre of 2€ and ring of 1€: 75% copper, 20% zinc, 5% nickel

Steel is mainly iron but the brown coins are plated with silver so it doesn't matter what the core is made of does it? My inspiration for making a voltaic pile came after watching an episode of Breaking Bad where the battery of their caravan goes dead out in the desert and they manage to get it started with a voltaic pile made from change. You'd probably need a pile the height of a house to get 12V but I like the idea of being able to produce voltage with coins all the same.
 
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The problem, as I understand it, has nothing to do with the composition of your coin electrodes, but rather with the connections between each cell and the solutions used for each half reaction. You can get some respectable voltages with those metals but you also need solutions of the corresponding ions. Sea salt is just about the poorest choice!
 
It is possible to get decent voltage just from two nails (copper/iron) put into a lemon. My bet is that € coins are a bad choice, I would first throw away those two colored. Note that it doesn't matter what is inside, what matters is what is in contact with the electrolyte - so even if there is iron inside, but plated with copper, this still counts as copper electrode.

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I have found that graphite (very thick mechanical pencil lead) and zn work pretty well as electrodes.

Salt water can work as an electrolyte but I immersed the electrodes in a container full of it. It is not clear to me that you will get much ion mobility in just wet paper.
 
Original Volta pile was made with pieces of metal separated by cloth soaked in brine. Ion mobility is not that important when you need just voltage, but obviously high internal resistance will not let you get a decent current.

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methods
 
Wait, how can a voltaic cell work on simple brine if one of the reactants in the net ionic equation is an ion of an electrode metal?
 
Ask Volta :wink:

When there no ions potential of the half cell (as given by the Nernst equation) is infinite. That's a pretty strong impulse to oxidize some of the metal in the presence of any (even weak) oxidizing agent.

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OH! I remember Nernst now! It will make a voltage, but a terribly weak one. Thanks.
 

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