Bubbles

Concept: Surface Tension 
Surface tension is caused by the cohesive forces between the molecules of a liquid. Surface tension happens because the liquid molecules in the surface layer are attracted to the bulk of the liquid beneath them. The result is the thin elastic "skin" on the surface layer of liquids. Surface tension is also responsible for the spherical shape of drops of liquid.

Read Aloud: Cool Chemistry Concoctions by Joe Rhatigan

Ingredients:

      ·         6 tbl. Water

      ·         2 tbl. Dish Soap

      ·         1 tbl. Corn Syrup

      ·         Paper Bowl
      ·         Plastic Bottle

 Demonstration:

      ·         Pour 6 tablespoons of water into a paper bowl.
      ·         Add 2 tablespoons of dish soap to the paper bowl.
      ·         Add 1 tablespoon of corn syrup to the paper bowl.

      ·         Mix the ingredients together but do not stir vigorously enough to form bubbles.

      ·         Dip the cut off end of a plastic bottle into the paper bowl. Blow through the opening of the bottle so that a bubble forms on the end of the bottle.

Experiment:

·         What happens if glycerin is added to the solution?

·         What happens if baking powder is added to the solution?

Observations:
When air is blown into the solution, the molecules in the liquid want to stay attached to each other so they wrap around the burst of air to stay connected. This is what makes the round bubble shape. The air inside the solution is pushing the molecules in the solution apart but the attraction between the liquid molecules is so great that the bubble does not pop.