Surface Tension: Lab Experiment

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• Published : November 8, 2010

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Surface Tension
Steven Brignol
Dr. Payne
September 15

Introduction: Water’s ability to stick to itself is surface tension. In this lab we were able to measure and detect surface tension by dropping water, drop by drop, onto a penny. The quantity of droplets that fit on the penny was impressive.

Hypothesis: The detergent will thicken the water making a tighter surface tension.

Prediction: If soap increased the surface tension, then expansion will happen.

Materials: (1) Pipette (2) Water (3) Penny (4) Liquid Soap

Method: Retrieve materials, and set two pennies onto the table. Using the pipette drop as many drops as you can onto the penny until it spill over. Record the amount into your data, and repeat four times. Once completed, average the trials and record the data. Repeat the same steps with soapy water. Drop as many drops on the penny with soapy water onto the penny and record the amount onto your data chart. After completing four trials, average them and record the data as well.

Results: Tap water has a greater average.

| Trial 1| Trial 2| Trial 3| Trial 4 | Average|
Drops of Tap Water| 23 drops| 12 drops| 17 drops| 13 drops| 16 drops| Drops of Soapy Water| 16 drops| 14 drops| 14 drops| 10 drops| 13.5 drops|

| Trial 1| Trial 2| Trial 3 | Trial 4| Average|
Drops of Tap Water| 14 drops| 22 drops| 13 drops| 12 drops| 15.25 drops| Drops of Soapy Water| 14 drops| 10 drops | 10 drops| 14 drops| 12 drops|

Conclusion: Soapy water allows fewer drops to be on the penny.

Questions:
(1) So many trials were taken and averaged so we could analyze the different types of data that will be retrieved. (2) The reason I obtained my results is because I observed that tap water expands at height and soapy water expands at width.

(3) If the experimental question was, “How does salt affect the surface tension of water?” I would answer that water absorbs salt and it’ll be able to hold more...