Eggmosis – Osmosis with Eggs

Posted by on June 21, 2011

A 2-for-1 experiment; Day 1 is an Acid-Base Reaction, Day 2-3 is the Osmosis Portion. Though it covers 3 days, the entire time spent on the project is 15-45 minutes.

DAY 1:

eggmosis1

Dissolving the shell
1) Place 4 eggs in a container, cover with white vinegar.
2) Add some “fresh” vinegar (or just replace with fresh vinegar)after about 8-12 hours.
Vinegar is an ACID; eggshells are made of calcium carbonate (BASE).

 

eggmosis 2

Reacting Acids and Bases
3) These are the eggs after about 2 hours. Look at all those CO2 bubbles!
4) You should have “naked eggs” (just the membranes) within 24-48 hours after starting
(For more on the chemistry: http://goo.gl/zOhCk)

 

DAY 2:

Eggmosis3

Naked Eggs
1) Remove and gently rinse your naked egg under running water. Compare it to a fresh egg. It looks (and feels) MUCH different now that the shell is gone!

 

Eggmosis4

2) Hold the egg up to light and look at the yolk. Boo said the egg feels like a water balloon.
3) Once the shell is off, the egg will get MUCH larger! This is due to osmosis – there is more water in the vinegar than in the egg. The water will diffuse from the area of high concentration (vinegar), into the area of low concentration (egg), across the membrane. Diffusion occurs until equilibrium occurs, (after that, exchange takes place at a steady rate).
(For an easy-to-follow definition and animation of diffusion and osmosis: http://goo.gl/IRxXi)

 

eggmosis5

Osmosis with Eggs
1. Label cups clearly for water, vinegar, and corn syrup.
2. Put one naked egg in each cup.

 

eggmosis6

3. Cover each egg with the appropriate liquid.

 

eggmosis7

Demonstrating Osmosis
Thing 2  helps Thing 1 demonstrate diffusion across a selectively permeable barrier. With Matchbox cars and a baby gate.*
After the demonstration, Thing 1 came up with his hypothoses:
1) The egg in corn syrup will shrink, because Corn syrup doesn’t have water in it. The water will diffuse from the egg into the syrup.
2) The egg in the vinegar will stay the same size, because it’s already been soaking in the vinegar long enough that it is in equilibrium (same concentration of water in AND out of the egg)
3) The egg in the water will get even bigger, since there is a higher concentration of water in the water (!) than in the egg.
*Large stuffed animals were also involved, but since this is a SELECTIVELY PERMEABLE barrier, they were unable to cross and stayed in a corner by themselves.
Edited: For that matter, the children are also unable to cross this particular selectively permeable barrier. Who says parenting isn’t a science.

 

DAY 3:

eggmosis8

Osmosis Eggs
Having soaked overnight, the eggs are dramatically different in size and feel.
1) The naked egg soaked in corn syrup is the smallest
2) The naked eggs soaked in vinegar and water aren’t significantly different from each other, visibly. However, you can tell a distinct difference by touch (the naked egg soaked in water is much more taut).
This observation seems to confirm Andrew’s hypotheses from yesterday, but the fun isn’t over yet!

 

eggmosis9

Observation

3. How are the eggs different? How are they similar? What do you think caused the differences?

 

eggmosis10

The egg soaked in corn syrup looks much different than the fresh egg, too.

 

eggmosis11

Breaking the Water Egg
Scientists always make the best of any “woops”. This is true.

 

eggmosis12

This surprised us! The absorbed water hadn’t been incorporated into the egg white or yolk. You can see the white and yolk intact in the middle of the huge splash of water. All of that water (plus the water on the boys’ shirts, plus the water on the floor) was inside the naked egg.

 

eggmosis13

Breaking the Vinegar Egg
Squeezing till the egg broke was a bit grosser than he expected it to be (sometimes science is messy).

 

eggmosis14

Breaking the Corn Syrup Egg
Because I’m the mean mommy, I didn’t let him squeeze this egg ’till it popped.
He *really* wanted to.

 

eggmosis15

More Observation

1) Look at the membrane (the consensus is that it feels like a flower petal).
2) Compare the volume of the broken Corn Syrup Egg to the volume of the broken Vinegar Egg. It’s pretty impressive; I wish we would have thought to measure the volume.

 

Who gets a Brownie Point? Did you notice we started with 4 Naked Eggs and finished with 3? That was my fault, not the kids!

51 Responses to Eggmosis – Osmosis with Eggs

  1. pirdzius

    gerai cia su kiausiukais,megstu ir as experimintuot,taip pat labai megstu kiausiukus.Dar yra viena,is virtu kiausiuku galima pasigamint duju.Reikia kiausiukus isvirt kietai,baltymukus atskirt nuo trynuku,aisku baltymukus suvakgyt.As labiau megstu truynukus kiausiuku,nes nuo ju gan daug perdziama ir bezdama.Taigi,toliaiu trynukus susmulkint,ydejus i inda padzivint kad sausi butu.Reikia kad butu sausi,kitaip trynukai prades paskui pelyt ir nedaug bezdaliuku gamins,reiks neuzilgo ismest.Taigi,isdziovinis jau susmulkintis trinukus toliau inde kokiam nors reikia laikyt siltai vis pastoviai.Paskui jau pradarius inda,ir kiausiku trynukai bezdosi jau,gaminamasi bezdaliukai.Reikai kad kiausiuku trynukai susmulkinti gerai isdziutu,tada bezdaliukai gaminsis gan ilgai,ilga laika.Ir reikia laikyt vis pastoviai kad siltai.Galima siu bezdaliku ysidejus i koki indeli ir i mokykla nusinest.Pradarei indeli ir jau bezdaliukai bezdosi.Galima ir i kunos kulkturos pamoka nusinest,isidejus ir treningiazu kisene.Sportiaskinatn kai kiek laisvo laikoa yra pradarei indeli ir jau bezdaliukai verziasi.Mes taip mokykloje su draugais ir draugem ir darom.Ir netik,bet ir istikruju pirdiaskinam ir bezdiaskinam,per kuno kulturos pamokas.Juoko buna visiems,pati ir kuno kulturos mokytoja juokiasi,kvatoja.Kartais ir pati tik pyrst pyrst

Leave a Reply

Your email address will not be published.