Adhesions and Cohesion

							 Bellwork:

Consider a lake in which the water is uniformly 10°C.
What happens to the oxygen-rich surface water as it
cools to 4°C? What concurrently happens to the
nutrient-rich deeper water?


 The oxygen-rich surface waters sink to the bottom of the
 lake as they are cooled down to 4°C. This is of benefit to
 the aquatic organisms living at the bottom. Concurrently,
 the nutrient-rich deeper waters are pushed to the surface.
 This is of benefit to the aquatic organisms living towards
 the surface. This process is called upwelling and is
 essential to marine organisms survival.
8.3 The Behavior of Liquid Water
    Is the Result of the Stickiness
    of Water Molecules
             OBJECTIVES
Define surface tension and discuss the reason
   for the high surface tension in water. 8.3.1
Explain capillary action. 8.3.2
  Cohesive Forces


The forces of attraction
between molecules of a
   single substance.
Paper clip
Cohesive
 forces    Paper clip
   Surface Tension


  The elastic tendency
found at the surface of a
          liquid.

     (cohesive forces)
 Soap reduces
surface tension
 Air




Water
   Adhesive Forces


 The forces of attraction
  between molecules of
two different substances.
Water
          meniscus

        The curving of
         the surface of
         a liquid at the
Water
        interface of its
           container
              meniscus

            The curving of
             the surface of
             a liquid at the
    Water
            interface of its
               container



concave
                     meniscus

                   The curving of
                    the surface of
                    a liquid at the
    Water
                   interface of its
                      container



concave   convex
Water
Water
            Adhesive
             forces


    Water



Cohesive
 forces
            Adhesive
             forces

    Water



Cohesive
 forces
Water
        Adhesive
         forces



Water
           Water



Cohesive
 forces
        Adhesive
         forces



Water
           Water



Cohesive
 forces
              Homework

pg. 266 RQ 14-18
  Due: F 11/09