Chemistry Extra Credit Labs
Alison Parrott
Mitchell Loop
La Salle Period 6
April 9, 2012
Surfactants
• Purpose
– The purpose of this lab is to observe an unusual
surface property of water that results from
hydrogen bonding using water and oil.
• Materials
– Bowl
– Water
– Paper clip
– Rubber band
– Dropper
– Vegetable oil
– Liquid dish detergent
Procedure
1. Thoroughly clean and dry the dish.
2. Fill the dish almost full with water.
3. Gently place the paper clip in the water and observe
what happens.
4. Repeat steps one and two.
5. Gently place the open rubber band on the water
6. Slowly add oil drop by drop onto the water encircled
by the rubber band until the water is covered with a
layer of oil. Observe for fifteen seconds.
7. Allow one drop of dish detergent to fall onto the
center of the oil layer. Observe for fifteen seconds.
Analyze and Conclude
• What happened to the paper clip in Step 3?
Why?
The paper clip sank to the bottom of the bowl.
• If a paper clip becomes wet, does it float?
Explain your answer?
– No, the paper clip still sinks because the mass is
great enough to break the surface of the water.
• What shape did the rubber band take when
the water inside it was covered with oil? Why
did it take the observed shape?
– The rubber band took the shape of the
surrounding oil because the oil can float on top of
the water because of the apparent hydrogen
bonding within the water and the contrasting
effects with the oil.
• Describe what happened when dish detergent
was dropped onto the layer of oil.
– The soap remained solid while it sat on top of the
oil layer. After some time, the detergent sank
below this layer and dispersed itself throughout
the water.