• Question: Why is universal indicator called universal indicator

    Asked by to Michael, Andrew on 23 Jun 2014. This question was also asked by .
    • Photo: Michael Kelly

      Michael Kelly answered on 23 Jun 2014:

      I think its called universal indicator because it can indicate the full or at least a larger range of pH than litmus or methyl orange. You might want to ask your science teacher though.

    • Photo: Andrew French

      Andrew French answered on 23 Jun 2014:

      Good question! Having just done a bit of reading around, it may will we that before Univeral indicator, we had to rely on multiple other indicator solutions for different purposes, which used different colours and weren’t clear. ‘Universal’ on the other hand suggests one indicator is good for a variety of tasks. This is mentioned in a very old scientific paper (1937!):

      “the observer may have difficulty in interpreting the many
      separate color changes met with in covering a wide pH
      range. This is, of course, due only to the lack of
      familiarity of the spectators with the indicators used,
      but rarely are demonstrations carried out with audi-
      ences having the necessary experience. A universal indicator,
      on the other hand, has the advantage that
      only one indicator solution (and one set of color stand-
      ards) is needed. After the significance of the color
      changes has been explained, the audience has little
      difficulty in following and interpreting the phenomena
      observed.”
      (http://pubs.acs.org/doi/abs/10.1021/ed014p274)

      But I could be wrong!

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