Marshmallows in a vacuum

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Hi everyone, its the mom here, with my first Stuff to Teach Our Kids post.

I really like baking, the kids like mixing and licking the bowl. I also like teaching them how and why we mix the ingredients together and the reactions that take place when certain things mix. Baking really is just science. So I went looking for some fun baking experiments we could try.

I came across this video by The Crazy Russian Hacker about what happens to marshmallows in a vacuum. It looks like a really fun experiment to try at home and you can find a vacuum box like the one he uses on Amazon here. You can also make your own vacuum box using a wine bottle and a wine saver pump/stopper (instructions here).

According to Physics.org the science behind the growing marshmallows is as follows:

Marshmallows have small bubbles of air trapped inside them. These bubbles are at atmospheric pressure. When the air inside the glass container is sucked out, the volume of the container remains the same although there is much less air inside – so the pressure is reduced. The air bubbles inside the marshmallows are therefore at a much higher pressure than the air surrounding the marshmallows, so those bubbles push outwards, causing the marshmallows to expand. When air is let back into the glass container, the surrounding pressure increases again, and the marshmallows deflate back to their normal size.

As soon as we get the vacuum boxes we are going to try this out for ourselves and I will post a video of our results. Please let us know if you try it out too.

Image credit: Marshmellows by Maryam Abdulghaffar, licensed CC BY 2.0

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