How does Helium escape from party balloons?
In: Physics
Helium is the smallest “molecule.” It’s a single atom, compacted by a relatively high nucleus charge/size ratio.
It’s so small and so chemically inert that the gas molecules can escape directly through the balloon material, wiggling their way in between other much larger molecules on their quest for freedom.
So no matter how well you tie off the bottom, the helium will eventually escape a cheap latex balloon. Materials with more compacted molecules like mylar will hold it longer, but even that is only slowing the inevitable.
Helium is super small and rubber balloons have tiny holes in them, which get larger when inflated. Those holes are large enough for helium to escape through and the balloon deflates over time
Helium atoms are smaller than the molecular make-up of the ballons. They in essence slip between the cracks. Add to that that most traditional ballons are elastic and forced to expand under pressure meaning the helium is always trying to find a way to the lower pressure on the other side of the balloon wall.
Mylar balloons on the other hand are made up of material more impervious to the leaking Helium. Add that they are mostly pre-inflated, so once enough helium leaks out they can hold the gas at a much lower pressure.
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