Australia's Science Forum

Can anyone tell me the procedure to dissolve an egg shell leaving the membrane intact? I think you use 1M HCl??
Thanks
Kathryn

Hi
I usually just soak them in vinegar over night.

Yes we also use vinegar.

Yep, just vinegar. It takes me more than overnight though. I usually flip it around a bit to make sure all of it dissolves (it floats for a while so the top isn't in it and then sinks so whatever is touching the bottom is also not dissolving)

Pardon my ignorance but why do you want to take just the shell of the egg?

Judith

Because it looks really cool??

I just asked a teacher. Has something to do with removing the calcium so you still have an egg but no strength in the shell... You can see the inside of the egg pretty well too

yes it does look pretty cool, and feels cool too.

I thought it was to show diffusion - I have supplied the eggs and salt water and electronic balances.

I believe the students weighed them, then soaked them in salt water and weighed them again....its a stinky one....

We use 6M HCl - it is fast - needs to be watched , eggs need to be moved so time intestsive. they work better that way than using vinegar or 1M HCl overnight - the vinegar makes the eggs swell and reduces the effectiveness of the osmosis (the point of the prac).

I've used Golden Syrup

What do you mean you've used Golden Syrup?? To remove the eggshell? We had 2 eggs in 1M HCL but it didn't work very well, which is why I put the question up. I've now got some in vinegar - hope that works better. Yes they are for the osmosis experiment.
Kath

The Golden syrup is used in the second part of the prac. After you have removed the shells of the eggs you put one in water which will cause the egg to swell and one in Golden syrup which will cause the egg to shrivel.
I've never tried one with saltwater, do you get a good reaction?

Cheers
Kelli

The teacher was happy with the results...so i guess that means the right thing happened.

My prep room is the hive of activity of ' trying stuff' today...its a buzz, i love it..who knows we may even make a scientific discovery

Oh Narelle, I LOVE those days!

OK here's a question for you - What do you do when you manage to prepare your eggs EARLY?? Do you leave them in water? I have never had this 'problem' before as I am usually still trying to get the last of the shell off the lesson before it's needed!! The eggs are now looking more like goose eggs than chicken eggs...

Rosalie,

I've only prepared the eggs 24 hours early. I put them in the fridge on moist paper towel in a closed container. They were fine.

Ev

I have prepared them as early as 3-4 days and put them on moist paper on airtight ( or just closed) container.
I have used acid before, but if too strong, the protein part of an egg hardens , looks like hard boiled egg, so now use vinegar and start first thing in the morning, and may have change vinegar half way through, but it is done by going home time.
Have a good weekend
Lada

This is the first time we have done this prac and I don't think it worked well. I soaked the eggs for about 11/2 days in vinegar and most of the shell was gone and the membrane was almost see through. We then soaked them overnight in H2O and 5% and 10% salt solutions. All the eggs increased in size. I'm not sure this was supposed to happen. Any tips on what to do to improve the outcome??

I just leave them in the vinegar in the fridge.

Till needed that is.
Wash gently under running water then carefully place in a beaker of water. Swirl a highlighter into a
the water.
The colour will be taken up by the egg leaving the water clear.
One for the Y6's.

Lorrae,
I think water, and weak salt solutions will increase the size of egg, but golden syrup or conc salt and sugar solutions will decrease the size.
Lada