If you bite in to a marsh mellow you will
notice that kind of looks like a tiny sponge, with
stretchy fibery bits and air pockets in between.
These are good qualities if you want to make it
expand, since the fibers are willing to stretch
and the air pockets can help push apart the fibers
as the marshmallow grows.
So, the question
becomes "what can we do to expand the air pockets
in the marshmallow?".
To answer that
question we can use a series of equations (Boyle's
Law, Charles' Law and the Ideal Gas Law) to see
how different factors like pressure and
temperature can change volume of air trapped in
the marshmallow. Or, we can think about the
experiments that were done to come up with all
those laws and come up with the same answer
without the math. Though math is
Here are my questions to you:
Is cold air more or less dense than warm air?
(If you had two balloons ofthe
same size but one was filled with really hot air
and one with really cold air, which would be
(if you had two balloons that were
filled with the same amount of air, but the air
was hot in one and cold in the other which balloon
would be bigger?)
2) Is air under pressure more
or less dense than air under low pressure?
If a balloon was attached to
an anchor and pulled to the bottom of the sea,
would it be bigger or smaller than when it was on
When a gas is cold the gas
molecules do not have as much energy to zip around
very quickly, literally, bounce of the walls of
the container they are in or each other. This
means that they stay closer together and don't
take up as much space. You can also push gas
molecules together if you reduce the size of their
This gives us three ways to
increase the volume.
Heat it: put it in the
microwave. (This is the classic but you are
obligated to clean up any mess you make. Tip: wait
till the goo cools down for a bit before cleaning.
Sugar burns are not a pleasant way to end an
Decrease the surrounding
pressure: put it in a vacuum chamber (excellent
results but expensive) or in an empty glass bottle
and use one of the rubber corks that comes with a
pump to reseal wine bottles.
amount of air in each pocket. (Also true but we
did talk about this above.) This is more
complicated to pull off and have never seen it
done. It requires forcing more gas into each of
the tiny pockets inside the marshmallow. I have a
few Ideas and I will get back to you...I am off to
the lab.Hope this helps.
Answers: cold air
is more dense than hot air. The cold balloon would
be heavier. The cold balloon would be smaller. Air
under pressure is more dense. The balloon would
shrink as it was pulled deeper due to the