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Home » Science Experiments for Kids » Biology » Osmosis and Shrinking Eggs!

Osmosis and Shrinking Eggs!

Modified: Jan 18, 2023 · Published: Aug 29, 2011 by Emma Vanstone · This post may contain affiliate links · 15 Comments

Welcome to a very eggy week on Science Sparks! Shrinking eggs is the first of 3 egg based experiments, so if you like this one, pop back later in the week to see what else we have been up to! This experiment looks at osmosis.

Osmosis is the net movement of water molecules across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration.

Water molecules flow from one side of a membrane to the other until the concentration of water molecules on both sides is equal.

What you need:

  • Two eggs
  • Water
  • Two glasses
  • Vinegar
  • Sugar
  • A pin

This experiment has 3 stages:

Remove the shell from the egg with vinegar

Shrink the egg by placing it into a concentrated sugar solution

Grow the egg by placing it in water.

Remove the shell from an egg

We need to remove the shell to expose the semi-permeable membrane of the egg. This can be done by placing the eggs in a cup of vinegar, so they are totally covered for about 24 hours. After this time wash the egg rubbing away the remaining bits of the shell.

washing the shell from an egg aftre it has been soaked in vinegar

Shrink and grow the egg

Make up a concentrated sugar solution by dissolving sugar in water. Place one egg in a glass of water, and the other in the sugar solution. Our sugar solution looks quite dark as I used brown sugar. Note how the egg in the water sinks to the bottom of the glass while the one in the sugar solution floats. This is because the sugar solution is denser than the water.

eggs with no shell sat in a fluid of water and concentrated sugar solution. The egg in the sugar solution floats. The shell has been removed by soaking the egg in vinegar
  • Leave for another 24 hours. You can see the egg in the sugar solution looks much smaller than the one in the water.
Two eggs with no shell. One is swollen with water and one shrunken as it has been soaked in sugar water

Prick the egg from the water with a fine needle and watch a jet of water shoot out!

A jet of water shooting out of an egg with no shell swollen from being soaked in water
  • Put the shrunken egg in water and watch it grow as it reabsorbs the water, this might take a few hours.

Why does the egg shrink and grow?

The sugar solution is much more concentrated than the water, this is because it contains dissolved molecules of sugar. The dissolved sugar molecules cannot pass through the semi-permeable membrane of the egg, but the small water molecules can. The water moves from the less concentrated egg solution to the more concentrated sugar solution until the concentration of water is the same on both sides. Therefore water moves from the egg to the sugar solution, and the egg shrinks.

When the shrunken egg is placed back in water, the concentration of water inside the egg is lower than the water, so water moves from the water to the egg, making the egg increase in size.

When we pricked the egg that had been in the water, water shot out of the egg. This is because the egg has absorbed water, and so the inside of the egg is under more pressure than usual.

The egg shell dissolves in the vinegar as the acetic acid in the vinegar reacts with the calcium carbonate of the shell. Carbon dioxide is given off during this reaction so you should see bubbles of gas escaping.

Extension Tasks

Weigh the eggs after removing the shell, after they shrink and again after they reabsorb water to see how much water is lost and gained at each stage.

Try adding food colouring to the water and watch as the eggs absorb the coloured water.

Soak a boiled egg in vinegar, this should make the egg so rubbery it will bounce ( from a low height ). You can also bounce a non-boiled egg that has been soaked in vinegar.

Don’t forget to wash your hands after handling raw eggs!

Image of an egg which has been swollen in water and one which has shrunk in a sugar solution

Last Updated on January 18, 2023 by Emma Vanstone

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Safety Notice

Science Sparks ( Wild Sparks Enterprises Ltd ) are not liable for the actions of activity of any person who uses the information in this resource or in any of the suggested further resources. Science Sparks assume no liability with regard to injuries or damage to property that may occur as a result of using the information and carrying out the practical activities contained in this resource or in any of the suggested further resources.

These activities are designed to be carried out by children working with a parent, guardian or other appropriate adult. The adult involved is fully responsible for ensuring that the activities are carried out safely.

Reader Interactions

Comments

  1. HELEN

    August 29, 2011 at 6:31 pm

    this looks great….I won’t promise to do it as I still have 2 avocado stones on my kitchen table!

    Reply
    • ScienceSparks

      August 30, 2011 at 12:41 pm

      Do it!!! xx

      Reply
  2. Crystal & Co

    September 05, 2011 at 2:31 pm

    How interesting. Thanks for linking up and sharing this idea on my site.

    Sharing a link over on Facebook.

    Reply
  3. Sandy

    January 25, 2012 at 3:59 pm

    Do you use hard boiled eggs? How does the egg not break when removing the shell? Does the vinegar cook it? Thanks

    Reply
    • ScienceSparks

      January 25, 2012 at 9:24 pm

      The egg is not cooked inside, it is liquid, the vinegar removes the shell, but leaves the outer membrane which keeps the egg in tact.

      Reply
  4. Anna Randals

    April 14, 2012 at 7:46 pm

    What age is this appropriate for?

    Reply
    • ScienceSparks

      April 15, 2012 at 1:39 pm

      My children were 3 and 4 at the time, I did everything for them, but they were very interested in it.

      Reply
  5. crystal@growingajeweledrose

    June 19, 2012 at 3:00 am

    Oh wow! What a neat experiment! Thank so much for sharing with Tuesday Tots. Pinned 🙂

    Reply
  6. Chattalie

    November 28, 2012 at 7:31 pm

    This looks really cool!
    How much sugar did you use for the solution ?

    Reply
  7. Carolyn

    March 19, 2013 at 5:06 pm

    These all look like fun! My 11 yod and I were just wondering how long do you soak the hardboiled egg in vinegar to be able to make it rubbery and able to bounce?

    Thanks!

    Reply
    • ScienceSparks

      March 20, 2013 at 2:12 pm

      It usually takes a couple of days and you’ll need to wash away the shell remnants.

      Reply
  8. Please correct the article

    March 09, 2015 at 9:49 am

    Sorry but I’m a biology student yr11, osmosis is actually the diffusion of water from a high concentrated region to a low concentrated region. I’m sure you made a mistake because my textbooks and what I’m being taught all the opposite of what is in your statement. Correct me if im wrong, I did this experiment last week and I’m writing a lab report and needed some more explanation from the internet. Sorry, wouldn’t want other people getting confused.

    Reply
    • sarah

      July 20, 2017 at 8:18 am

      hi Dear. where in the text did you find the wrong statement opposite to the osmosis law, i.e., water diffusion from high to low concentration?
      maybe by the term concentration which was only used for the sugary liquid and it meant -i think- the concentration of big sugar molecules, if it is high then the water is low and if they are low, then the water is high. so you’d actually need to reverse the low/high adjectives to define how much water you have, if you were reading that part about the sugary liquid
      So i guess whenever you see the term concentration, just imagine they ar talking about the sugary liquid and not the water (pure water)

      Reply
    • sarah

      July 20, 2017 at 8:20 am

      hi Dear. where in the text did you find the wrong statement opposite to the osmosis law, i.e., water diffusion from high to low amount? pls notice: amount and not concentration. The term concentration is only used in the sentences regarding the sugary liquid here and not the pure water
      maybe by the term concentration which was only used for the sugary liquid and it meant -i think- the concentration of big sugar molecules, if it is high then the water is low and if they are low, then the water is high. so you’d actually need to reverse the low/high adjectives to define how much water you have, if you were reading that part about the sugary liquid
      So i guess whenever you see the term concentration, just imagine they ar talking about the sugary liquid and not the water (pure water)

      Reply
  9. shall

    May 02, 2017 at 2:37 am

    very fun and love you guys

    Reply

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