DAY 1 BUBBLES OF CARBON DIOXIDE BEGIN TO FORM ON THE EGG SHELL.|
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DAY 7 A TRANSLUCENT EGG IS LEFT AFTER THE SHELL HAS DISSOLVED.|
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is a classic experiment with eggs. If you soak a raw egg in vinegar, over the
course of time, the vinegar will dissolve the eggshell. What you’re left with
is the egg’s translucent membrane to protect the egg. Since the shell is made
up mostly of calcium carbonate.-- it contains calcium carbonate (94%), magnesium
carbonate (1%), calcium phosphate (1%), and 4% organic matter-- vinegar which
contains acetic acid will dissolve the shell.
the egg in a tall glass or jar and cover the egg with vinegar. Wait a few minutes
a look at the jar. You should see bubbles forming on the egg. Leave
the egg in the vinegar for a full 24 hours in the refrigerator. After the 24 hours,
carefully pour the old vinegar down the drain and cover the egg with fresh vinegar.
Place the glass with the vinegar and egg back in the refrigerator for a full week.
One week later pour off the vinegar and very carefully rinse the egg with water.
The egg looks translucent because the outside shell is gone. Notice that some
of the vinegar has permeated through the egg's membrane and caused the egg to
get a little bigger.
egg shell is composed of calcium carbonate (CaCO3). When calcium carbonate comes
in contact with vinegar which contains acetic acid (CH3CO2H)
a chemical reaction occurs.
first thing that happens is that the carbonate (CO3--) part
of calcium carbonate is protonated by acetic acid to make carbonic acid (H2CO3).
Along with this
, the calcium and acetate from calcium acetate.
CH3COOH + CaCO3 = H2CO3 + Ca(CH3COO)2.
In the next step, the carbonic acid breaks down to form carbon dioxide and water,
H2CO3 = H2O + CO2.
overall reaction is just to sum of the two reactions given,
CH3COOH + CaCO3 = H2O + CO2 + Ca(CH3COO)2.
CaCO3(s) + 2CH3COOH(l)
Ca(CH3COO)2(s) + H2O(l) + CO2(g) Water
and excess vinegar evaporate upon standing. Carbon dioxide (a gas) is released
into the air during the reaction.
you dissolve the eggshell, the egg is surrounded by a membrane. (Actually, it’s
two membranes, but they are held tightly together). To get a better idea of see
Anatomy of an Egg.
does a naked egg look and feel like? See this mpg
from University of Iowa.
to go from here?
are some excellent classroom experiments using naked eggs that demonstrate diffusion