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Pour Water Down A String
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Science Area:  Chemistry
Content:  Cohesion 

Down the Spout

 

Materials:

1 quart pitcher

Water

Food coloring

String made of cloth

Clear drinking glass

 

Procedures:

 

1.   Fill the pitcher halfway with water and add food coloring.

2.   Soak the string for a moment in the water, then take it out and let it drain back into the pitcher.

3.   Tie one end of the string to the handle of the pitcher. 

4.  Set the glass on a flat surface approx. 2 feet away from the pitcher.

5.  Slowly pour a trickle of colored water down the string and into the glass.

 

Questions:

1.  What did you expect to have happen?

2.  Why was it necessary for the string to be wet?

3.  What forces were holding the water to the string?

4. What other materials can be used in place of the string?

5.  Is it possible to pour other liquids along a string such as vegetable oil or soda pop?  If so, would you expect the same results?

 

 

Explanation:

 

The molecules of some substances are attracted to the molecules of other substances.  This is called adhesion.  When the string is wet, the water molecules are attracted to the molecules of the string.  Once the string is wet and more water is poured down it, the water molecules on the wet string and the molecules of the water being poured will cling together.  This is called cohesion.  Water is a cohesive substance. 

 

 

 

Source:  Pearce, Q.L.. Kitchen Science Experiments.  Lowell House.  Chicago, IL. 1999.  p.49.