Module 2 Intro

1. Module 2 Intro

1.14. Page 2

Lesson 3

Module 2—Chemical Compounds

Explore

In previous science courses you learned about the unique properties of water, including its high surface tension and high boiling point. You may recall hearing that these properties were due to the polarity of the water molecule. How can you test to see if a molecule is polar? Complete the next investigation to find out.

Try This: Bending a Stream of Water

Can you cause a thin stream of water from a tap to bend without actually touching the water?

Materials

a plastic object (e.g., a bendable plastic ruler, plastic ballpoint stick pen, or comb) or a balloon. The balloon works best, especially when you rub it on your hair.
a piece of cotton (e.g., a tea towel or cotton shirt) or a piece of fur

Procedure

Step 1: Rub the plastic object with the cotton or fur or rub the balloon in your hair. Make sure you rub vigorously to build up a good static charge on the object.

Step 2: Turn on the tap to allow a thin stream of water to pour out. Kitchen taps work well. The thinner the stream, the more observable the change will be.

Step 3: Bring the plastic object close to, but do not touch, the stream of water. What do you notice? Record your observations.

Step 4: Record your observations when you approach the stream of water with the plastic object from the opposite side.

Step 5: If you have a piece of wool handy, try rubbing it on the plastic object. This will place an opposite charge on the object. Repeat Steps 3 and 4. Record your observations.

Save a copy of your data to your course folder. You may wish to refer to your investigation and your data later in this lesson. Send a second copy of your data to your teacher.