I4-12. Boiling Water By Pumping

Purpose

To demonstrate that water boils at a lower temperature under reduced pressure.

Equipment

Beaker of water and vacuum pump with bell jar.

Suggestions

Some of this effect may be simply from the air dissolved in the water coming out do to the action of the pump.

Images

Description

Place a beaker of water in the bell jar attached to a vacuum pump. Turn on the pump and the water will begin to boil. Discuss the necessity of boiling food longer to cook it at higher elevations. Talk about bubble chambers and cosmic rays influencing when bubbles first appear in the liquid. Tell the story about Donald Glaser, Nobel Laureate, getting the idea for the bubble chamber by watching bubbles form in a glass of beer.