Chemical Changes

Bonnie J. Hickerson            Horace Mann
                               8050 S. Chappel
                               Chicago IL 60617 
                               312-535-6640

Objectives:

Grade 6

1.  To investigate some characteristics of chemical changes.
2.  To learn that a chemical change changes the composition of the substance.
3.  To learn that the formation of gas bubbles is an indication of a chemical 
    change.
4.  To learn that a color change is an indication of a chemical change. 
5.  To learn that the disappearance of color is an indication of a chemical 
    change.

Materials needed:
    
  For each class:

1.  Apple                            8.  Toothpicks
2.  Clear plastic cup                9.  Knife                 
3.  Vinegar                          10. Popcorn popper
4.  Baking soda                      11. Grapes
5.  Clorox bleach                    12. Water 
6.  Food color                       13. Paper
7.  Household hydrogen peroxide      14. Popcorn         

Strategy:

1.  Put 1/4 cup of vinegar in a clear plastic cup.  Add a teaspoon of baking soda 
    to the vinegar and observe. 
2.  Cut an apple in half and observe the exposed section's color immediately.
    Observe again after a few minutes.  Observe what happens to the inside
    color.
3.  Put one drop of food color into a clear plastic cup and add 1/4 cup of water.  
    Mix with a toothpick and observe the color.  Put some Clorox bleach in 
    another cup and add some bleach to the food color using a medicine dropper.  
    Keep mixing with the toothpick and observe what happens to the color. 
4.  Put a quarter cup of household 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.
5.  Place popcorn in a popper.  Examine some of the extra kernels.  Observe the 
    kernels exploding as the water inside turns to steam. 
6.  Put a few grapes in a container, add sugar and yeast.  Stir, let stand
    for a few days and observe.

Performance Assessment:

    Your family will vacation in Dakar, Senegal.  As a student of science you 
will be given the opportunity to work at a junior chemistry laboratory. You must 
pass a test before you are hired at the Senegalese laboratory.  Your challenge 
is to classify a list of chemical and physical changes, and be able to give your 
reason for each choice.  You may use charts and diagrams. 

List the Chemical and Physical Changes:
    1. Burning of a building
    2. Adding sugar to lemonade
    3. Water changing to steam
    4. Rusting of iron
    5. Fluffy egg whites
    6. Leaves changing color
    7. Milk turning sour
    8. Faded cloth
    9. Churning of milk
   10. Baking rolls
   11. Ripening of tomatoes
   12. A stick broken into small pieces
   13. Growing vegetables
   14. Formation of a gas bubble
   15. Disappearance of color
   16. Making ice cream
   17. Using hot water to expand a metal cup
   18. Opened canned fruit left out of the refrigerator for a few days
   19. Digestion of food
   20. Popcorn popping
   21. Freezing water

   Guidelines for Scoring:
   Students who classify 18-21 changes correctly will be eligible to acquire the 
job, and will receive a grade of A.  17-14 = B, 13-10 = C, 9-7 = D, 6 and below 
is an F.