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That's a long page, so you can optionally jump to the "Thunderstorm it" part, but a bit of context is always neat :)

Context

Say I'm cooking an egg in vinegar. The egg shell is made of calcium carbonate:

$$\ce{CaCO3 + CH3COOH -> H2O + CO2 + Ca(CH3COO)2}$$

After eating the egg, is left in the cookware: a bit of calcium acetate, lots of water, acetic acid and other unidentified stuff.

It'd be neat to isolate that calcium acetate, as it could be of use sometime. I've seen that we can grow cool looking crystals out of it, maybe I could try that! Anyway chemistry is cool, so let's do it :)

But there will also be loads of water (egg cooking). I could store it all, but that wouldn't be very practical...

Getting rid of the water

I see three ways to get rid of that water.

Boil until water evaporates

Energy-hungry process. I'm a kind of environmental-crazy dude, so that's not an option.

Filtering

While boring, that could be an efficient option, if at all possible. It seems calcium acetate is soluble in water. Is there a way to filter it out without expensive equipment, or even at all?

Electrolysis

Energy-hungry as well, but I have a spare solar panel that produces 6 or 12V and anything between 0 and 4W, so that energy comes for free (albeit quite slowly in Belgium).

Thunderstorm it!

No matter how feasible are the other options, I'm here to experiment, so I'd love to do some electrolysis :) I got time anyway!

Constraints

I have very little knowledge of chemistry (but eager to learn!), and no equipment at all, except for household items. Also, this experiment would take place in living space (probably in my room), so it should be safe to do (e.g. do not produce chlorine gas or other nasty products). And if it's not smelly, it's even better :)

How I would do it

I'll need:

  1. container: a drinking glass should suffice
  2. anode
  3. cathode
  4. some electrolyte in the water
  5. electricity: the solar panel will provide what's needed
  6. time: we all have a pool of that in our life

I still need the anode, cathode and electrolyte. And also, I'd love to understand the process that takes place.

In my younger age, I used copper wire as both anode and cathode, table salt as electrolyte, and it would produce tiny bubbles on one end of the wire, and go green on the other end (do I remember properly?).

In this experiment though, the context is a little different:

  • I need to "dissolve" a lot of water, so just a copper wire won't be enough
  • It seems that using NaCl as electrolyte produces chlorine gas instead of oxygen, that's pretty bad

Choosing the electrolyte

Since I cooked the egg in vinegar, I'll probably have some acetic acid left in the water. Would that be a good enough electrolyte? Alternatively, I have baking soda readily available, but that would produce other salts when reacting with the remaining acetic acid...

Choosing the anode and cathode

I'm lost here. First and foremost, I remember my copper wire going green when doing electrolysis. Does that mean I'll "consume" my anode/cathode while doing the electrolysis? That sounds pretty expensive. Also, I'll have to separate calcium acetate from copper oxyde afterwards...

Questions

  1. is the above reflection correct at all?
  2. what's the best choice for electrolyte and anode/cathode materials
  3. what's the exact reaction taking place?
  4. any other way to isolate that calcium acetate?
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  • $\begingroup$ Buy some small reverse osmosis unit and do the thickening with it. $\endgroup$ – Jaroslav Kotowski Jun 17 '15 at 9:34
  • $\begingroup$ Interesting! I'll have a look at that :) $\endgroup$ – aspyct Jun 17 '15 at 9:38
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How to get rid of water to collect calcium acetate?

Evaporate it.

How to do it in an environmentally responsible way?

  • Electricity from the outlet cost you money and probably used some combination of coal, natural, gas, and or nuclear to produce it.

  • Bunsen burner, but it likely uses a fuel that was taken from the ground, made from a crop that that competes against food production for land.

  • Solar cells to produce electricity. It uses renewable energy but is relatively expensive and electricity is a high value energy compared to solar thermal. Using commercial grade solar cells only converts about 17% of the energy in sunlight into electricity that is then converted into heat to evaporate the water.

  • Solar thermal is cheap and easy to make with household items like an aluminum or soup can and black spray paint. Further more, it has the potential to be more than twice as efficient as solar cells at providing energy you need to evaporate water.

Electrolysis:

If you insist on electrolysis for experimental reasons, calcium acetate is a salt of acetic acid and calcium from the calcium carbonate in the egg shells. As a salt, like all salts, calcium acetate will dissolve in water forming ions that will conduct electricity. So, there is no need for any electrolyte other than water and calcium acetate.

Furthermore, your end products will be something other than calcium acetate and would depend in part on your anode and cathode, temperature, and applied voltage.

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  • $\begingroup$ Welcome to chemistry.SE! If you had any questions about the policies of our community, please ‎visit the help center. $\endgroup$ – M.A.R. Jun 23 '15 at 15:34
  • $\begingroup$ Wow, I didn't even think of just exposing it to sun. Points for the easiest solution ;) thanks also for the info on the electrolysis, and especially about the "won't be the same part". I'll investigate :) $\endgroup$ – aspyct Jun 23 '15 at 15:45
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    $\begingroup$ I'm not completely sure, but I think that the products of electrolysis will be something like: $\ce{H2}$ + $\ce{C2H6}$ + $\ce{CO2}$. $\endgroup$ – sadljkfhalskdjfh Mar 26 '16 at 11:43

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