Materials:
-Two clean test tubes
-One waxed test tube
-Mercury
-Water

Fill one test tube part way with water and the other with mercury. Fill the waxed test tube part way with water. Observe the shape of the liquids at the top of the column and how it connects with the test tube.

The water in the clean glass test tube curves upward while the mercury curves downward. Water experiences a force of adhesion with the polar glass molecules and so starts to wet and climb the walls of the test tube. This upward movement is counteracted by gravity and thus the downward curve is formed. Mercury does not experience an adhesion with glass and so the surface tension of mercury and its aversion to glass causes it to form an upward curving meniscus. The water in the waxed tube should form a meniscus similar to that formed by the mercury for similar resons. There is no adhesion between wax and water and forms the upward curving meniscus.


http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/property.html

Back Home