Water Cycle - Water (5) Lab
 OBJECTIVES: Discovering density. Comparing the density of water to that of other liquids. VOCABULARY: clean up density oil oil spill water MATERIALS:  plastic vials  ice water  hot water  salt water  food coloring  small dish  soap  cotton swabs  colored pencils or crayons  container  craft sticks Students experiment with liquids of different densities.
 BACKGROUND: Water is so common to students that they can't see its special properties, but water (without any additives) has characteristics that make it unique.  It has a high boiling point, low freezing point, is tasteless, and odorless.   The density of a substance is the mass of that substance compared to the volume that the substance occupies.  Density will vary depending upon the temperature.  The density of water as a liquid is higher than that of water vapor.  Other substances have other densities, in this lab we want the students to compare the different densities of certain liquids while comparing them to water.  After the students complete the density portion of the lab, they can start thinking about the effects of oil pollution on water.  Oil will float and cause a problem for organisms that live on the surface. PROCEDURE: This activity looks at the different densities of different liquids and how this information can be useful knowledge when cleaning an oil spill.  Water is so common to students that they can't see its special properties, but water (without any additives) has characteristics that make it unique.  It has a high boiling point, low freezing point, is tasteless, and odorless.      Write the chemical formula of water on the board and explain the components that make up water, namely, hydrogen and oxygen.  Ask the students what the natural states of matter hydrogen and oxygen are usually found as (Gas).  Make sure they know and understand the role of water in the water cycle.    The students should have a tub of water and they should pour oil on it representing an oil spill.  Give them 3 substances:  soap in a small vial, craft sticks, and an adsorptive substance like cotton swabs or crepe paper.  Have the students design a way to capture the oil and clean up the spill.    Hopefully they learned that because oil is less dense than water it will float on the water.  The oil can actually be "scraped" from the surface of the water and cleaned in that manner.      Discuss the effects of contamination and oil pollution on the environment, wildlife, and humans.  After your discussion talk about some possible clean-up methods and how these methods might be useful.