Walking Water

Concept: Capillary Action
Capillary action describes the spontaneous flow of a liquid into a narrow tube or porous material. It is caused by the combination of the cohesive forces of the liquid and the adhesive forces between the liquid and the narrow tube or porous material. These forces pull the liquid into the tube. This is how plants bring water up through their roots to their stem and leaves.

Read Aloud: Big Book of Science Experiments by TIME for Kids

Ingredients:

      ·         Water

      ·         Food Coloring

      ·         Paper Towel

      ·         Mason Jars

 Demonstration:

      ·         Choose two colors of food coloring to mix.
      ·         Fill two mason jars with water. Add a different color of food coloring to each jar.
      ·         Place an empty mason jar in between the two jars containing colored water.

      ·         Fold two paper towels lengthwise and put one end of each into a jar containing colored water and the other end of each into the empty jar.

Experiment:

·         What happens if you use another brand of paper towel?

·         What happens if you vary the temperature of the water?

Observations:
Capillary action draws the liquid up into the paper towel and saturates the paper towel. The water travels upward by flowing into the pockets of space surrounding the cellulose fibers in the paper towel. The areas around the fibers help draw the water up, allowing it to "climb" out of the full cup and back down into the empty cup. Quilted paper products are often more absorbent than their counterparts because the quilted shapes offer more pockets of space for water to flow into around the fibers.