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Chemical changes occur when substances become new or different substances. Fireworks like those in the QuickTime video at the right, that we see on the 4th of July are actually metals such as magnesium and copper that change chemically as they light up the night skies with their fantastic colors. To identify a chemical change look for observable signs such as color change, bubbling and fizzing, light production, smoke, and presence of heat.

 


Drag your mouse over the link to watch a QuickTime video of the reaction of vinegar and baking soda. Remember to close the new window that it opens in to return to this page.

You can observe a chemical change each morning if you fry an egg for breakfast. Drag your mouse over the link to view a short QuickTime video clip of an egg frying! Remember to close the window when you finish viewing the video to return to this page. The presence of heat can cause a substance to change chemically. Remember that whenever you cause a chemical change, the substance that you begin with cannot be chemically the same as the substance that you end up with. It is true that the egg does not change into an apple but your raw egg is definitely not the same in structure as a cooked egg.

One of the major evidences of a chemical change is that the substance has been altered chemically.

 

Anaylsis:

  1. What is one piece of evidence that indicates the egg underwent a chemical change?
  2. Is the cracking of or breaking of the outer shell of an egg a chemical change?
    • Why did you make this decision?
  3. When you eat the egg for breakfast, is the digestion process based on chemical or physical changes?
  4. What evidence do holiday fireworks provide to prove that a chemical change occurred?

Review science lab safety rules here.

Get the plug-ins: Get Adobe Acrobat Reader , and Get Quicktime Player (The QuickTime plug-in is needed to play sounds and movies correctly.)

Want to share photos of you or your friends doing this activity? Send it in an e-mail with the following information: the title of the activity, the URL (Internet address), and your name. Remember that no pictures can be used which show any student faces or has a student name on it.

Updated August 13, 2005 by: Glen Westbroek

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