A Simple
Indicator
Needed:
- Slices of a fresh beet
- Water
- A pan
- Heat
- A drinking glass
- Substances to test
Experiment:
Put half a glass of water into a pan. Put three or four
slices of beet and boil for five minutes. Let the red liquid
cool, and pour some of it into the glass. Test various substances
to see whether they are acid or alkaline. If alkaline substances
such as alum water or ammonia are added, the color turns to yellowish
green or brown. If an acid such as lemon juice or vinegar is
added, the reddish color returns.
Explanation:
Indicators are natural colors from plants which show one
color with an excess of H+ ions from an acid and a different
color with an excess of OH- ions from a base. Litmus is
the most common indicator in laboratories. The exact mechanism
of the color change is not thoroughly understood. Test
different substances found in your home to see if they
are acids or bases. Try cleaning products, food products,
or other ideas you come up with.
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