Consider the following indicators and their pH ranges: Methyl orange 3.2-4.4
Methyl red 4.8-6.0
Bromothymol blue 6.0-7.6
Phenolphthalein 8.2-10.0
Alizarin yellow 10.1-12.0
Assume an indicator works best when the equivalence point of a titration comes in the middle of the indicator range. For which of the following titrations would methyl red be the best indicator?
a) 0.100M HNO3+0.100M KOH.
b) 0.100M aniline(Kb=3.8×10^-10)+0.100M HCl.
c) 0.100M NH3(Kb=1.8×10^-5)+0.100M HCl.
d) 0.100M HF(Ka=7.2×10^-4)+0.100M NaOH.
e) 0.100M acetic acid(Ka=1.8×10^-5)+0.100M NaOH.