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Mystery of the CO2 Balloons! Answered

Filled some balloons w  co2  from dry ice in a soda bottle.  

As expected, they act like a lens, a magnifier of sound. No mystery there. Just as a dense glass refracts light, the denser gas refracts sound.

The mystery is why balloons filled with co2  leak down faster than identical balloons filled by mouth. Yes, there is some co2 in my exhaled breath, but it is mostly  n2,  and  o2.  I would hav expected the n2 and o2 to leak out more quickly, being smaller molecules. So whatzup wit dat?


Um... the dry ice starts of very cold.

This is just speculation, but if the temperature drops below the glass transition phase of the rubber, it may fracture slightly, allowing gas of any kind to escape more quickly?

Do the balloons deflate as quickly if you re-inflate them with your own breath?

i thought i had protected the balloon from cold by putting dry ice in soda bottle instead of directly in balloon. i even put that soda bottle in a bowl of hot water to speed things up.

im testing your hypothesis. most of the balloons i tied, making refill by breath impossible, but one was just twisted off and clamped with clothespin. This one ive refilled with breath. so far it is holding.

could moisture in breath act to seal micro holes in balloon?

I really don't know. It's a fascinating thought experiment, though.

The balloon which leaked down in 2 days when filled with co2 has, when refilled with breath, held air for 2 weeks.

Next test: will a baloon with a little moisture in it hold co2 ?