|MadSci Network: Physics|
The ordinary soap bubble solutions are made of chemicals which evaporate rather quickly. What this means is that when you blow a soap bubble with them in the air, the thickness of the film is very small and you note that in a minute or less normally the bubble breaks. That is because as the film evaporates if becomes thinner and thinner and less weak, so that it then breaks under the stretching force of the higher pressure air inside the bubble. If the bubble were blown in vacuum (if possible to do) the film would evaportate very much more quickly because there is not air present on the outside to slow down the evaporation and so the life of the bubble would probably be very very short. However even more complicated, blowing such a bubble in a vacuum would be very difficult. Remember the bubble grows because the air pressure inside the bubble is greater than that outside the bubble and this higher pressure causes the bubble skin to stretch out.(normal air pressure). The easiest way to envision making such a bubble is to first imagine that you have a vacuum chamber with a pipe going through the chamber wall into the room, and with a valve on the room-end of the pipe. Then you can inject a drop of soap-bubble liquid into the pipe through the valve. valve. The liquid would be drawn through the tube towards the vacuum and when the drop reached the end of the tube it would form a film over the end of the tube and a bubble would form there. The bubble would begin to form immediately and grow in vacuum depending upon the rate of evaporation of the liquid on the inside of the pipe. It's life would depend on how fast the liquid evaporates away from the outside surface of the bubble into the vacuum. In this way you should be able to make bubbles in vacuum but their lifetime may be very short!
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