You have 2 solutions, pH7/pH9,which indicator to use to identify each, methyl orange or phenolphthalein?

Question

Choices

Niether one would be a good choice

or

Phenolphthalein

Answer 1

Phenolphthalein begins its active range around pH8.  This would let you pH9 solution turn pink while your pH7 solution remains clear.

Answer 2

phenolphtahlein is pink at 8.1-8.3 and quite red at pH 9 so it woul work well at the elevated pH listed.Methyl orange has an acidic pH range in its color transitions and is distinctly red at pH 3.6  orange at pH 4 and yellow at pH ~ 4.4 or so.MO would not be a useful indicator at either pH