MadSci Network: Physics
Query:

Re: What is the correct hypothesis for the egg in the bottle experiment?

Date: Mon Feb 23 08:51:01 1998
Posted By: Dan Berger, Faculty Chemistry/Science, Bluffton College
Area of science: Physics
ID: 888007391.Ph
Message:

If I understand you correctly, the experiment is one in which

  1. a bottle is heated slightly;
  2. a shelled, hard-boiled egg is placed on top, narrow side down, so as to seal the top of the bottle; and
  3. the bottle is chilled in an ice/water bath.

What should happen is that the egg should be sucked into the bottle. This is caused by the contraction of the air inside the bottle (with consequent lowering of pressure) as it is chilled; the outside air pressure then forces the egg into the bottle.

What the experiment is designed to show is that the pressure of air (the air inside the bottle, naturally) becomes lower when its temperature is reduced. So a "correct hypothesis" [see below] would be "the pressure of a given quantity of air is/is not reduced when its temperature is lowered."

A caveat (which Ms. Porcelain may know about, but I am inserting for other readers of this answer): make sure you use a glass bottle with a rather thick, smooth rim, such as a (formerly corked) wine bottle. Plastic soda bottles probably won't work for two reasons:

For the second reason, I also would avoid screw-top glass bottles.

I wish you luck; if scientists can be musicians (and both I and Nobel-Prize-winner Jean-Marie Lehn, who is a fine pianist, are examples), there's no reason a musician can't teach science!

  Dan Berger
  Bluffton College
  http://cs.bluffton.edu/~berger


NOTE: I don't particularly like this way of teaching scientific thought; it seems to me too stiff and formal. Much scientific progress is based on someone saying, "gee, wouldn't this be neat if it worked?" or even, "gee, why didn't this work?" An example of the latter is Perkin's discovery of the first synthetic dye, mauveine.


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