1. Pour about 15 ml (about 1 tablespoon) of salt into a clear plastic cup. Place the cup on a scale and find the weight of the cup and the salt.Record the weight.
2. Fill the cup about 1/3 full of hot tap water and stir until all the salt has dissolved.
3. Using a permanent marker draw a line at the level of the water and place the cup where it can remain undisturbed while the water evaporates.
4. Make a prediction (Hypothesis): What will happen to the salt when the water evaporates?
5. Check the cup daily. If you notice any changes record your observations.
6. When the water has completely evaporated,record your observations of the cup. Weigh the cup and the material in the cup. Record the weight.
7. Answer the following questions:
   • How does the weight of the cup after the water evaporated compare with the weight of the cup and the salt before the water was added? Explain why.
   • What is the material in the cup?
   • Was your prediction correct?
   • When the salt dissolved in the water, was it a chemical reaction or a physical change? How do you know? (It was a physical change because all of the salt was still there when the water evaporated. There were no new substances formed.)

Tell students that 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. 

Product:

Students will be able to recognize if a chemical change has occurred.

This CD is packed with over 100 science experiments, 1,000 science problems and 60 off-computer experiments, plus parent help and print-outs. Curricula for grades 2-5 are included.

With this amazing CD kids will discover astonishing facts and important principals. Science grades will go up, up, up.