Alcohol in a vacuum: Testing Experiment

Aim

The following experiment tests whether the air absorbs the drying liquid. If this mechanism is correct, then what would happen to a piece of paper wetted with alcohol and then placed under a vacuum jar? Will the alcohol disappear as before?

Prior Knowledge

The first two videos and accompanying questions of this sequence.

Description of the Experiment

Two pieces of paper are wetted equally with alchohol. One is placed in the open air and another is placed under a belljar and the air is pumped out. When the vacuum is sufficiently high, the pump is turned off and the tap is closed, sealing of the bell jar from the outside. (Watch the inset to see this happening.) Note: Since evaporation is a lengthy process, the video is played back at 4 times normal speed.

Before you watch the video predict which piece will dry first based on the explanation/mechanism that the air absorbs alcohol.

Youtube movies can be stepped frame by frame using the , and . keys on your keyboard. If you want to download the movie to your computer, right-click or control-click HERE.

Questions

Describe the outcome of the experiment. Did the outcome of the experiment match the prediction based on the mechanism of the air absorbing the alcohol? How should you revise the mechanism to account for the results of this experiment? How would you test the new mechanism?