Chemical Changes

Grade Level(s): 6, 7, 8

OVERVIEW: The students will compare different types of chemical changes.

PURPOSE: By doing the following demonstrations, students will gain an understanding of how chemical reactions produce new substances.

OBJECTIVE(s): STUDENTS WILL BE ABLE TO:

Tell what a chemical change is.
List some of the chemical properties of common materials.
Understand how chemical changes affect their lives.
Be aware of some of the dangers of chemical changes.
BACKGROUND INFORMATION:
Chemical changes occur all the time in our daily lives. Chemical change causes a new substance to be formed from two or more different elements or compounds. Students need to have some understanding of elements and compounds when you do these experiments.

RESOURCES/MATERIALS:
You will need the following materials:

iodine
alcohol
starch
iron nail
yeast
sugar
milk
vinegar
toast
toaster
hot plate
small sauce pan
I usually catch students interest by doing a demonstration that show how explosive chemical changes can be. I put one half of an alkaseltzer tablet in an old plastic 35 mm film container. Add a small amount of water and put the lid on.

PLEASE MAKE SURE ALL STUDENTS ARE STANDING AWAY FROM THIS DEMONSTRATION, ALSO DON'T PUT THE CONTAINER DIRECTLY UNDER A LIGHT FIXTURE.

The following reaction will create some discussion. This is where I discuss the dangers of chemicals and their reactions.

ACTIVITIES AND PROCEDURES: You may choose to do the following as a class demonstration or if you choose you could have each student do the reactions. I believe it would be important for students to record observation and make some conclusions from those observations when they are done.

IF YOU CHOOSE TO LET EACH STUDENT DO THESE EXPERIMENTS, BE SURE THEY HAVE REVIEWED BASIC LAB SAFETY RULES. Listed below are some examples of materials and chemical changes that can be demonstrated with them. Discuss chemical changes developed by you or the students during the experiments. Be sure to discuss with the students how these chemical reactions affect their lives during or right after the demonstrations and/or experiments.

Add the following materials to each other to create the desired chemical reaction:

Material Chemical Changes

iodine changes to brown in alcohol change to blue in starch
wood ashes make into potash, water released
toast burn until charcoal
iron rusting of iron with water
lime quick lime changes to slaked lime
yeast forming of carbon dioxide in water
sugar heat changes to caramel
milk add vinegar to curdle

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