To my surprise, it works better than those dual-pointed text highlighter/eraser combos.
I always thought that erasable highlighters had a different kind of ink, but it seems like some citric juice is enough to erase them.
How does this work?
In: 2
Presumably it’s because of the pH of the citrus juice. Color change induced by pH is a very common phenomenon, there are many different indicator compounds that change color at a very specific pH. Phenolphthalein is a very common indicator, that is colorless in a solution with a pH below 8.5 but is bright pink above a 9.0
Color changing indicators are how litmus paper is made, which is paper made specifically for testing the pH of a solution. The litmus paper I’ve seen turns red for very alkaline solutions (high pH) and very dark for acidic solutions (low pH). Litmus paper is so ubiquitous that a “litmus test” is slang for getting a quick reaction from someone.
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