Hi! And welcome to another edition of
Kitchen Chemistry. I’m Julie, an educator
with the New Mexico Museum of Space
History, and today we are going to be doing
an experiment that deals with Chemistry and
Earth Science. All you need is a few items
you have around your house. The things you
need today are salt, you are going to need
some water, you are going to need two
quarters, a small glass or a small glass bowl
that can fit into a large bowl. They need
to be
glass and not plastic so that they stay in
the
water and don’t float. You’re going to
need
some scotch tape, blue food coloring, a
spoon and some plastic wrap. So go gather
up all those items and join me right back
here. 97% of the water on the earth comes
from
the oceans. Ocean water is not pure enough
to drink. It is mixed with different substances,
like salt that make it unsafe to drink. Our
experiment will show a simple way to get salt
out of water. First you need to put water
in
your bowl and take a dry erase marker and
mark the water level on the outside of the
bowl.
Next we are going to make our simulated
ocean water. Put several drops of blue food
coloring in the bowl and 3 heaping
teaspoons of salt in the bowl and stir until
all
the salt has been dissolved. Remember that
water and salt combined is a mixture. A
mixture is two substances that are physically
combined but the parts keep their own
physical properties so they can be separated
again.
Next put your glass bowl or cup into the
middle of you ocean. I tried to use my glass
bowl, but it was too light so it floated on
the
surface. The glass was heavy enough to not
float. Then cover your bowl with plastic wrap
and tape it to the sides of the bowl. Make
sure that the plastic wrap is not tight on
your
bowl, but should slightly sag in the middle.
Then tape the plastic wrap all the way
around your bowl so that no air can get in
or
out.
Place the two quarters on the plastic wrap
directly over the cup. Place the bowl on a
flat
surface in a warm place, like a windowsill,
outside or under a heat lamp. Now comes
the hard part, wait for at least 4 hours.
You’ll
notice that even under the lights in my studio
the plastic wrap is already starting to fog
up.
The heat helps the water to change from
liquid to vapor. The water vapor rises to
the
plastic wrap and then cools off and
condenses back into liquid form. The
droplets will slide down the plastic wrap
and
land in the cup. The salt is to heavy and
it
will stay in the ocean. After 4 or more hours,
take the plastic wrap off and take the glass
cup out of the water. Observe if the water
level is lower or higher than at the beginning
of the experiment. Did you collect any water
in your cup? Is the water clear or blue? This
device we made is called a solar still and
it
uses the energy from the sun to take the salt
out of the water. This process is called desalination.
Scientist use the concept of a
solar still to work on how to take ocean water
and make it potable or drinkable water.So
did your solar still work? Did you collect
some fresh drinking water leaving the salt
behind? Well, thank you for being with me
for
another edition of Kitchen Chemistry. And
don’t forget to like and subscribe to our
YouTube channel, as we’re always adding
new information and new projects. And as
always, stay home, stay safe, and keep
looking up.
