A Flask Contains Nothing

Material Round flask with outlet, stopper and stop cock, syringe, water jet-pump (water aspirator), large glass bowl. 

Procedure Remove 50 ml of air from a round flask by sucking it out with the help of a syringe, then close the flask by the stop cock. Once again attempt to remove 50 ml air. When it becomes too difficult to further remove air with the syringe, then attach a water-jet pump and let the water run for a minute. Dip the outlet of the closed flask into the glass bowl under water and open the outlet. 

Observation A certain amount of air can be removed from the round flask through the use of the syringe, low air pressure is thereby created. After the rest of the air is removed using the water-jet pump, a vacuum results in the flask no air or other material is left in the flask. If one opens the outlet of the flask under water, it fills completely with water. 

Engida, T., Sileshi, Y. Concept Cartoons as a Strategy in Learning, Teaching and Assessment Chemistry. Addis Ababa, Ethiopia, 2004 

Stachowiak, H. Gedanken zu einer allgemeinen Theorie der Modelle. Studium Generate 18 (1965), 432 

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