Jam Experiment
Needed:
- Blackberry jam or jelly
- Warm water
- Ammonia
- Lemon juice or vinegar
Experiment 1:
Put a spoonful of the jam or jelly into a glass of warm water.
Once dissolved, the color is probably red. Put a few drops
of ammonia into the glass and the color changes to greenish
purple.
Experiment 2:
Add just enough ammonia to produce the greenish purple color.
Then, add lemon juice or vinegar to see the color change back
to red.
Explanation:
Many colors from flowers and vegetables can serve as indicators.
An indicator is something that tells whether a substance
is acidic or alkaline (basic). The jelly solution acts as
an indicator. When acid is added, it turns red. When an alkali
is added, it turns greenish purple. The color change results
from a chemical reaction where excess H+ ions (from acidic
substances) produce one color and excess OH- ions (from basic
substances) produce a different color.
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