Science experiments for children – Growing and shrinking egg: the term osmosis indicates the passage of the liquid part between two solutions that have different concentrations, through a semipermeable membrane. The liquid tends to pass from less concentrated solution towards the more concentrated. Osmosis is therefore a spontaneous, physical process which tends to dilute the more concentrated solution, and to reduce them difference in concentration.
In other words when on the two sides of the membrane are solutions at different concentrations, the osmotic pressure difference moves the molecules from the less concentrated solution (hypotonic) to the more concentrated solution (hypertonic), until the concentrations in the two solutions become identical (isotonic).
For this experiment we need a naked egg, which is obtained as better explained here taking dipped in vinegar a raw egg (perfectly intact) for at least a day.
Already during this preparatory phase of the experiment you can observe the phenomenon of osmosis. We measure the egg before you dip it in vinegar (height with a ruler, the diameter with a string) and after.
The naked egg will be enlarged than egg with shell because the water contained in the vinegar is moved to it. In fact there are more substances dissolved in the water inside the egg of than there are in the vinegar.
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Science experiments for children – Growing and shrinking egg
First variant
What do you need?
a naked egg,
a jar with lid,
salt,
a piece of string and a ruler.
What to do?
Pour water in a jar filling it about ¾ and add salt, stirring, until the salt does not dissolve any more (saturated solution).
Measure the naked egg then dip it into the jar, close and let it sit for a few days.
Remove the egg from the jar and re-measure the circumference.
The naked egg, after being dipped in water for a long salt, it will be shrunken.
What happens?
The phenomenon of osmosis has caused the transfer of water from the egg (less concentrated solution) to the salt solution (more concentrated).
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Science experiments for children – Growing and shrinking egg
Second variant
What do you need?
2 plastic bags for foods with zip,
a syrup of light color (eg malt),
a naked egg,
a bowl full of water,
ruler and twine for measurements.
What to do?
Fill a plastic bag for about half with the syrup, put in the naked egg and close.
Lay everything in the bowl of water to prevent breakage and leave it for three days.
Remove the egg from the syrup, wash it gently and measure: the egg will be shrunken so as to appear withered, and you will hear the yolk inside.
Now half fill another bag with water, and put the egg shrunken. Let it sit for a few days: it will return to its initial size.
What happens?
In the first phase of the experiment the water passes through the membrane from the egg to the syrup (which is more concentrated) and the egg dehydrates. In the second phase, the process is reversed.
Science experiments for children – Growing and shrinking egg
Third variant
What do you need?
a naked egg,
a transparent glass jar,
syrup or molasses.
What to do?
Immerse the naked egg in the jar filled with syrup: the egg must be covered.
Leave it in the jar for about 3 days. The egg will be smaller.
Rinse, soak in a pot full of water alone and wait another three days the egg will be back to normal.
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Science experiments for children – Growing and shrinking egg
Fourth variant
What do you need?
two naked eggs of the same size,
water,
two glasses,
sugar,
a pin.
What to do?
Prepare a saturated solution of sugar and water in a glass and immerse one of two eggs.
Pour another glass
just water and immerse the second egg.
Let stand for at least a day.
As explained above, the egg dipped in sugar solution will be shrunken and the egg soaked in water will be larger.
Try to prick the egg enlarged with a pin: from the hole will come out a jet of water.
Now you can throw away the egg pierced and try to put the egg shrunken in water for another day, to see it return to its original size.
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Science experiments for children – Growing and shrinking egg
Other links
http://dragon.sleepdeprived.ca/
http://www.hometrainingtools.com/
http://www.science-sparks.com/
http://www.cmste.uregina.ca/Quickstarts/shrinkingegg.html
http://mommasfunworld.blogspot.it/2013/03/3-egg-science-experiments.html
http://the-science-mom.com/242/shrink-an-egg-science-demonstration-osmosis/
