Chemical Changes

Geraldine Smith                Delano School
                               3937 W. Wilcox   
                               Chicago IL 60624
                               (312) 534-6620

Objective:

The students in grades 3-8 will be able to explore some properties of Chemical 
Changes. 

Material Needed:

Medicine dropper                 Vinegar
Baking soda                      Green food color
Hydrogen peroxide                Tooth pick 
Clear plastic cup                Bleach
Apron                            Safety goggle
Apple                            Knife

Strategy:
     One way of describing the characteristics of a pure substance is by its  
chemical properties.  A chemical change produces a new substance with different 
chemical properties.  Chemical properties help you describe the way one 
substance will chemically react with another substance.  Color changes, solid 
formation, bubble of gas formation, and color disappearance are indicators of 
chemical changes.  In this experiment you will look at some chemical changes. 

Experiment 1
Cut an apple into two sections.  Observe the exposed area immediately.  After 
ten minutes observe what happens to the inside color.  The oxygen in the air 
reacted chemically with the apple and caused a color change. 

Experiment 2
Pour a quarter cup of vinegar into a clear plastic cup.  Add a teaspoon of 
baking soda to the vinegar and observer.  The vinegar reacted chemically with 
the baking soda and produced bubbles of carbon dioxide. 

Experiment 3
Put a drop of green food color in a clear plastic cup.  Add a half cup of water.   
Mix with a toothpick.  Place some bleach in another cup using the medicine 
dropper.  Add 30 drops of bleach to the water and green food color.  Observe 
what happens.  The bleaching of the green color by the bleach is an indication 
of a chemical change. 

Experiment 4
Place a quarter cup of hydrogen peroxide in a clear plastic cup and add a slice 
of apple.  Observe the slice of apple and check for the formation of bubbles. 
The decomposition of hydrogen peroxide to produce oxygen as one of the products 
is an example of a chemical change. 

Performance Assessment:
The student should receive 25% for each experiment done correctly.