SURFACE PROPERTY AND HYDROGEN BONDING

Amber Sager

PURPOSE

To observe an unusual surface property of water

that results from hydrogen bonding

MATERIALS

shallow dish or Petri dish

water

paper clip

rubber band, approximately 5 cm in diameter

micropipets or droppers (2)

vegetable oil

liquid dish detergent

PROCEDURE

Thoroughly clean and dry the dish.

Fill the dish almost full with water. Dry your hands.

Being careful not to break the surface, gently place

the paper clip on the water. Observe what happens.

Repeat Steps 1 and 2.

Gently place the open rubber band on the water.

Slowly add oil drop by drop onto the water encircled by

the rubber band until that water is covered with a layer of

oil. Observe for 15 seconds.

Allow one drop of dish detergent to fall onto the center of

the oil layer. Observe the system for 15 seconds

CONCLUSION

While doing this lab I had a few challenges. I

couldn’t get the exact ingredients and the paper clip

was hard to get to float. When I did get it to float the

oil made it sink. The soap made all the oil break up.

A source of error was having to replace the Petri

dish with a container.

The paper clip in step 3 floated. If the paper clip

becomes wet I believe it can still float because of the

surface tension. The rubber band became an oval

because the oil spread it out.

When the detergent was dropped into the oil it

made the oil disperse and leave the rubber band

circle.