Australia's Science Forum

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

lada wrote: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

Yes. That is what should happen.

Water and weak salts solutions are hypotonic-- they're less concentrated than the egg-- so osmotic pressure will draw water into the egg.

Concentrated salt, sugar, and especially golden syrup are hypertonic-- they're more concentrated than the egg--so water will be drawn out. The syrup is very good at this; not much water content at all.

Thanks Everyone! I thought we may have done something wrong. Will try these alternatives next time!

Hey,
Just wondering. I've had the eggs in from the beginning of the day, how long does the process usually take to complete?
And is it bad if I leave them in the fridge still in the vinegar over the weekend to complete? Or will this just further break them down?
Thanks!

emma.hunt wrote: ↑21 Jun 2019, 14:02 Hey,
Just wondering. I've had the eggs in from the beginning of the day, how long does the process usually take to complete?
And is it bad if I leave them in the fridge still in the vinegar over the weekend to complete? Or will this just further break them down?
Thanks!

We've had ours soaking for a week in the fridge. That seemed a long enough time to dissolve the egg shell & get a good, firm membrane to start the prac with.

Several years ago, I only ever needed one or 2 eggs at a time and used a 250ml beaker. I’ve been asked for 6 eggs. Can they all go in one beaker (or ice cream bucket?) with the vinegar or is it better to do each one separately? I’ve got until Monday to get them ready.

I had to prepare 30 eggs this time. I think they need 24 hours in vinegar and it works better if you rub them a bit several times during the process as well as changing the vinegar at least once. I put 10 eggs in 3 large beakers.

Oh wow! 30!! OK I will try them in an ice cream bucket. I do remember needing to rub them a bit and changing the vinegar but it has been a long time since I had to do it!