6.disappearing ink serbian team regional center for talented youth belgrade 2
DESCRIPTION
Weak acids or weak bases Indicators are weak organic acids or bases that have different colors in their protonated and deprotonated states Phenolphthalein is a weak organic acid that behaves as an acid–base indicator It exists in two different forms - an acid form HInd, which is colorless, and a corresponding base form Ind –, which is pinkTRANSCRIPT
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International Young Naturalists’ Tournament
6.Disappearing InkSerbian team
Regional Center for Talented Youth Belgrade 2
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Suggest a chemical formulation for the ink that would disappear after used to write a text. What parameters determine the time when the text becomes invisible? Is it possible to process the -paper in such a manner that the text appears again?
6. Disappearing ink
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Weak acids or weak bases Indicators are weak organic acids or bases that have different
colors in their protonated and deprotonated states Phenolphthalein is a weak organic acid that behaves as an
acid–base indicator It exists in two different forms - an acid form HInd, which is
colorless, and a corresponding base form Ind–, which is pink
pH Indicators
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Ink formulationWater (100ml) Sodium hydroxide (5 drops of 6 mol\dm3 NaOH solution) Ethanol (20ml)Phenolphthalein (3g)
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CO2 + H2O → H2CO3
2 NaOH + H2CO3 → Na2CO3 + 2 H2O
Making of the ink
sodium hydroxide disappearing ink
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Parameters
Air circulation in the room
Air temperature
Base concentration
Carbon-dioxide concentration
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Orange juice Invisible inks that respond to heat
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baking soda + blueburry juice
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Thank you on your attention!!!
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Phenolphthalein-Experiment