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Changing Matter - Chemical Changes

Chemical changes occur when substances become new or different substances. Fireworks 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.

Watch this video of the reaction of vinegar and baking soda.

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.

Analysis:

  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?
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