Question

what happens when vinegar is added to plaster of paris

Answer 1

Mix a half teaspoon of vinegar into each quart of plaster you use on your next repair job, and the "mud" will take longer to set up, thereby giving you just that much more working time.
A Plaster Master or a Plaster Disaster, Page 1 of 2
Plaster of Paris has calcium carbonate in it and also contains
another chemical called calcium sulfate. Both these calcium
chemicals are used to make cement, Plaster of Paris, and
similar building materials that have to start off wet and then
harden. These calcium chemicals work well when mixed with
water so let's see how well they work when mixed with other
liquids.
Materials:
• Plaster of Paris
(Please follow all warnings on the Plaster of Paris
label.)
• 4 small disposable cups
• Water
• Salt
• Vinegar
• 2 Plastic spoons
• Wax paper
• Masking tape
• Pen
Procedures:
1. Label 3 cups water, salt water, and vinegar. Use
masking tape and a pen to label a piece of wax paper
water, salt water, and vinegar. Place a heaping
teaspoon of
plaster of
Paris into
each labeled
cup.
2. In another
small cup,
make a salt
water solution
by adding
about ½
teaspoon of
salt to 2
teaspoons of warm water. Stir until as much salt
dissolves as possible.
3. Add about 1 teaspoon of water to the plaster of Paris in
the water cup. Stir
until the plaster and
water are thoroughly
mixed. Add a little
more water or a little
more plaster until the
mixture is not runny
but thick enough that
it can be molded.
4. Scrape the mixture
out with a spoon and
use another spoon to
move the glob of
plaster into its labeled
area on a piece of wax paper.
5. Repeat step 2 and 3 using salt water and vinegar.
6. Wait about 5 minutes and gently press down on each
plaster glob with a spoon. What do you notice? Check
the globs in the same way again in 5 minutes and then
again in 5 more minutes. Which liquid seems to work
best with the plaster to make it hard? Which seems to
work worst?
Think about this…
Plaster hardens well when it is mixed with water and placed on
wax paper. Let's see if the wet plaster hardens if it is placed
under water!
Mix plaster and water the way you did in the activity to make a
nice glob of plaster. Then, instead of placing the glob of plaster
on wax paper, gently place it in a small cup about ½- full of
water. Check the plaster for hardness every 5 minutes for
about 15 minutes.
When the chemicals that make up plaster are thoroughly
mixed with water, the water and the chemicals begin to
interact with each other. The water works with the chemicals
as part of the hardening process which is called curing. In
curing, the water doesn't evaporate but actually becomes part
of the hardened plaster.
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