1. Surface tension is a force that holds the surface of a fluid together. It results from the cohesiveness of the liquid molecules. Explain what makes water molecules cohesive.

2. What characteristic(s) does a substance need to possess in order to be hydrophilic?

3. Explain why a column of water moved up the inside of the glass capillary tube in this exercise.

4. Explain why water behaved differently in the plastic capillary tube compared to the glass tube.

5.

a. Hand draw a line graph (no computer graphics!!) of the class average data that was collected in section III.B of today's lab. The x-axis should be the number of drops of detergent and the y-axis should be the distance between the top of the water in the test tube and the top of the water in the capillary tube. Your graph must be neatly drawn and your data points clearly marked with an appropriate symbol (a large dot, square, triangle, etc.). Use a straightedge to connect the data points together. Clearly label the axes of your graph and give the graph an appropriate title. Attach it to this sheet when turning in your assignment.

b. Explain why the detergent had the effect it did on the height of the water column.