Vinegar Vs.lemon for Dissolving Eggshells
Most recent answer: 02/04/2015
- Amanda Rice (age 45)
Berkeley, Ca, USA
Your son's results make alot of sense. Ordinary 5% vinegar is a little les than 1 Molar acetic acid. Because acetic acid is a weak acid,only a small fraction of it (about 1/2 %) actually comes apart into Ac- + H+ at that concentration. The pH is about 2.4. If you have citric acid from a lemon at that pH, it's mostly dissociated into citrate- + H+. Once you put the eggshell in, it starts reacting with the H+, as we described in the earlier answer (). That would raise the pH, causing more of the acetic acid to dissociate. There isn't much more of the citri acid left that isn't already dissociated. So all that spare acetic acid is available to react with the eggshell, and then with the egg. If you've used say 1/2 liter of liquid, you'll get almost a mole of H+ available for reactions from the vinegar but only about 0.01 mole or a little less from the lemon juice. So it's not just the pH that determine how much of the reaction will happen but also how much of the non-dissociated acid there is in reserve.
You had enough acid left to also pickle the inside of the egg, a your son described so well. I believe that the acid denatures the protein (albumin) in the egg white. The protein chains sort of unravel and get tangled up with each other. They can't just roll past eah other any more. That makes it bouncy. It's similar to what happens when you boil an egg.
(published on 02/04/2015)