I learned that litmus paper could be bleached by chlorine to turn colorless. I’m wondering if any chemical substances can react with all the components of a universal indicator such that it turns colorless, or stops being a pH indicator?

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    $\begingroup$ I would suspect the same chlorine bleach. Universal indicator consists of organic dyes. $\endgroup$ – Oscar Lanzi Oct 4 '19 at 10:01
  • $\begingroup$ @Oscar Lanzi really? I heard that chlorine just turns it purple or red $\endgroup$ – loadingnow Oct 5 '19 at 12:10
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    $\begingroup$ A fun demo is to make red cabbage soup, which goes from deep red at very low pH to deep violet at high pH, and then add a bit of chlorine bleach to turn it clear. $\endgroup$ – DrMoishe Pippik Oct 7 '19 at 1:04

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