Thanks for the great question! Soap makes
water form into bubbles because the soap forms a
very thin film that prefers to "coat" the
surface of the water that is exposed to air. The
reason for this is that, soap makes the
interface (the surface where water touches air)
between air and water more stable (longer
lasting, more likely to form). This explains why
so many bubbles form after stirring or agitating
the water: all of the bubbles you form while
stirring or blowing last much longer in soapy
water than in pure water. Also, you will notice
that the bubbles create much more area where the
water is touching air.
As a result, almost all of the soap will come
to the surface of the water if you let the water
sit still (no stirring, blowing into, or
otherwise agitating the water) for a long time.
Once the soap is at the surface, a vacuum can be
used to suck the soap off of the surface of the
water. Be careful to just get the surface layer,
since this is where the soap is! An interesting
side note is that we use this sort of technique
in the research lab for some experiments of our
I don't think that blowing into the water
will remove all of the soap without the vacuum.
However, try blowing into the water after using
the "vacuuming-the-surface" technique described
above. If you successfully removed most of the
soap, then the water should form less
Good luck with your interesting experiment!
Feel free to let us know if you are successful!