What happens to whipped cream in a vacuum chamber

The video below shows what happens when you put a small amount of whipped cream in a vacuum chamber and then suck the air out of it.

The reason is that whipped cream is mostly air and as you lower the pressure in the chamber, the air expands and takes the cream particles along with it.

It is fun to see but you do not need sophisticated apparatus to see similar effects. I used to do science demonstrations to middle school children to illustrate that air exerts pressure, which is a non-intuitive concept. One of the activites was to give them a plastic syringe (without a needle of course) and insert a marshmallow into it with the plunger pushing it until it just touches the nozzle. Then placing a finger over the nozzle end to prevent air entering, you retract the plunger thus reducing the pressure in the cylinder. The marshmallow expands to several times its normal size. When you allow air in again through the nozzle, the marshmallow deflates to a size much smaller that you started with since it had lost a lot of the air that had puffed it up.

The children loved it.


  1. sc_cf67521d06de66549b93107fecc68ecb says

    As a kid I tried depressurizing insects in a syringe but it didn’t seem to faze them. Thinking about it now, I suppose the exoskeleton of a small insect can withstand 10+ psi inside it.

  2. Johnny Vector says

    When I worked at Sea Data, we had a small pressure chamber made out of an old bomb casing, for testing up to 5000 psi (if I recall correctly). It was fun to put styrofoam things in it and pump it up. They didn’t recover when brought back to atmospheric pressure. I had a tiny styrofoam cup on my desk from that. The inside diameter was about 8″, so you could put in one of those foam heads they use to store wigs. For some reason the resulting shrunken head was really funny.

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