[Jaques]

hehe. Melting .(Correction not melting. but dissolving.)  again. Only this time Its actually happening.

No idea what brought this on, but I wanted to try melting the hard shell out of eggs. And I've been successful until now.

So I thought if it were possible to get rid of the shell by using only household material, and well seems like it is. I took a normal egg and put it in a glass cup with Vinegar (acetic acid 5-15%) and Lemon juice (citric acid) mix. The mix was mostly Vinegar, and well for the first few minutes nothing much was happening. But then It started fizzing and well smelling really "ughh".  And the reaction continued for awhile actually. like 2 days and 1 night.  And well the fizz wasn't exactly normal, it was all sticky and stuff. Kinda funky.  But by then the vinegar had diffused into the egg, since now the egg had a yellow-ish hue to it.   But that didnt' allow me to see the yolk, which would assure me that the shell was complelty gone and only the transparant membrane is there holding the egg. So now I'm diffusing the egg with water, hopefully that'll work.

But I just checked if I could see the yolk, and I can, but i have to put it up against light. So If anyone has any idea on how to make the yolk visible, I'm willing to try it.

And I have a question for you. I'm still in highschool chemistry, so this kinda puzzles me. Acid and acid don't react right? If so then, how come there was fizz?  Logically I assumed that the acids were reacting with the eggshell, and if that is true. Then what would be the chemical equation for this reaction?  Just wondering and trying to make this an "academic" experiment.

Okay now for the picture.


What you see in the picture is the midway point. I'll take a more recent picture soon. Hopefully showing the yolk.

And yeah, it is floating. But i don't think it's floating because of the egg getting lighter in density or the water . You see the little bumps on the egg? Those are little packs of air, and that was a result of the reaction, and it rose up like that. And for the whole day and night it stayed up, but by the second evening it went down, which is when i changed it from vinegar to water. And right now it is sitting in water. [

[Borek]

but I wanted to try melting the hard shell out of eggs

Dissolving, not melting.

[constant thinker]

An egg shell is like 95% Calcium Carbonate (CaCO₃). The rest is calcium phosphate, magnesium carbonate, and proteins.
http://antoine.frostburg.edu/chem/senese/101/consumer/faq/eggshell-composition.shtml

CaCO₃ is commonly used as an antacid. I wish I could tell you what the reaction was, but I don't know what the products are. I'm not very well educated in Organic Chemistry. Hopefully one of our Organic Chemists will read your question. I can tell you the gas that is being released is CO₂ though.

Also Borek is right. It's dissolve not melt.

[joeflsts]

A bit more info:

When you submerge an egg in vinegar, the shell dissolves. Vinegar contains acetic acid, which breaks apart the solid calcium carbonate crystals that make up the eggshell into their calcium and carbonate parts. The calcium ions float free, while the carbonate goes to make carbon dioxide—the bubbles that you see.

Joe

[constant thinker]

So what happens to the organic acid (acetic acid)?

 Is it just a catalyst from the decomposition of CaCO₃? Or does it get consumed?

Sorry I don't have much experience with Organic Chemistry.

[Borek]

So what happens to the organic acid (acetic acid)?

Is it just a catalyst from the decomposition of CaCO₃? Or does it get consumed?

Sorry I don't have much experience with Organic Chemistry.

What will happen if you use strong mineral acid instead of acetic acid?

[constant thinker]

OOO. Sorry. Now that I know the Ca will be left over the balanced equation should look like this:
4CaCO₃ + CH₃COOH -> 2H₂O + 4Ca + 6CO₂

Am I right. Like I've said before, I haven't done much work with Organic Chemistry as far as expirements and education.

I do know though that excessive C₂H₆O + person -> funny behavior + tipsy person.  

[Borek]

OOO. Sorry. Now that I know the Ca will be left over the balanced equation should look like this:
4CaCO₃ + CH₃COOH -> 2H₂O + 4Ca + 6CO₂

No. Please answer my question on strong mineral acids. Try with hydrochloric, as that's the simplest case.

[constant thinker]

The acid will be consumed in the reaction. Hydrochloric acid + Calcium Carbonate would look like:
2HCl + CaCO₃ -> CaCl₂ + CO₂ + H₂O

The calcium would become calcium chloride. The left over H's, C's, and O's would become H₂O and CO₂.

This is what would happen if you used a mineral acid, right?

[Borek]

2HCl + CaCO₃ -> CaCl₂ + CO₂ + H₂O

OK. Organic acids in this case will behave the same way - they are acids first, organic later Now try to write reaction of CaCO₃ dissolving in acetic acid - all you have to do is to replace hydrochloric with acetic.

[constant thinker]

5CH₃COOH + 4CaCO₃ -> 10H₂O + 4CaC₂ + 6CO2

I get stuck on the products. I'm not sure if it's CaC₂ or just Ca. Joeflsts says that Ca just floats away free, unless he's not looking at the full reaction.

I intended to ask about organic acids and how they react with bases awhile ago. I guess I'm asking it now.

Thanks for helping me on this Borek by the way.

[Alberto_Kravina]

5CH3COOH + 4CaCO3 -> 10H2O + 4CaC2 + 6CO2

Too complicated (and wrong)!!!  Actually, the same reation takes place only that calcium acetate forms instead of calcium chloride. Nothing happens to the acetate ion. This is no redox reaction!

Hint: write "HAc" instead of CH₃COOH (Where "Ac^- stands for the acetate ion (CH₃COO^-))

I'm not sure if it's CaC2 or just Ca

Neither CaC₂ nor Ca. The product is calcium acetate (CH₃COO)₂Ca

[pantone159]

Where "Ac^- stands for the acetate ion (CH₃COO^-)

I thought I have seen Ac used to refer, not to CH3COO (like you said, and which makes sense to me), but instead to CH3CO, so acetates are, e.g., HOAc.  I'm thus a little confused by what is meant by 'Ac' when I read it somewhere.

[Alberto_Kravina]

Yes! Ac can stand either for an acetyl group (CH₃CO) or for the acetate anion (CH₃COO^-)

[Borek]

Sometimes CH₃COO^- is written as AcO^- and acetic acid as AcOH.