The activity was also performed as a demonstration for AP
chemistry and chemistry high school students. The use of this
demonstration and the discussion that ensued in high school was
recorded and is available in podcast format via the Supporting
Information. The high school students examined the gaseous air
system before the liquidvapor water system as a review of
Boyle’s law and to provide a stark contrast to the vapor pressure
setup. Thus, when the volume of the air system changed, Boyle’s
law prevailed and the pressure of the system changed inversely
with the volume. When the setups were compared, the lack of
pressure change with volume change in the water setup provided
a discrepant event that forced students to reconcile the differences
and challenge their misconceptions. Discussion led to trying to
understand what was changing in the systems on a molecular level.
Students were able to conclude that the rate of condensation
momentarily changes as volume is changed, but then equilibrium
is attained again when the rate of condensation returned to equal
the rate of vaporization.