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