Methyl orange:
Changes from red at 3.1 to yellow at 4.4
http://en.wikipedia.org/wiki/Methyl_orange
Phenolthalein:
Changes from colourless to pink above 8.2.
However, it has other ranges of colour changes when pH is very low or very high.
http://en.wikipedia.org/wiki/Phenolphthalein
in what pH range do methyl orange and phenolphthalein change colour
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2 answers