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Secret Messages
How can acids and bases be used to write
secret messages? The teacher writes
a message, such a note, a word, or a homework assignment, in
lemon juice. Then a student sprays cabbage water on the chart
paper to reveal the message.
Materials
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 1 c water + vinegar OR
 1 c water + ammonia
 pitcher of cabbage
water (the purple indicator)
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 chart paper
 cotton
swabs
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What To Do
 DIP the cotton swab into the ink and use
it to WRITE your secret message on the soft porous paper. ALLOW
the message to dry completely.
 READ the "invisible ink" message
by MISTING it lightly with the spray bottle filled with the red
cabbage water solution.
Try making different messages with the different solutions.
Do they all appear the same way? In what ways are they alike
and different?
What's Happening? Find out more about invisible
ink.
Challenge. What other solutions can work as invisible
ink, or invisible ink revealers? Share your results in our pH Exchange.
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