Cliffs AP Chemistry, 3rd Edition

Appendix B: Acid-Base Indicators

Range Indicator Lower Color Upper Color

0.0−2.5 Methyl violet Yellow-green Violet

0.5−2.0 Malachite green HCI Yellow Blue

1. 0−2.8 Thymol blue Red Yellow


2. 2−4.0 Benzopurpurin Violet Red


3. 3−3.0 Orange IV Red Yellow


4. 5−2.6 Naphthol yellow S Colorless Yellow
   2.1−2.8 p-Phenylazoaniline Orange Yellow
   2.5−4.4 Methyl orange Red Yellow
   3.0−4.7 Bromophenol blue Orange-yellow Violet
   3.0−5.0 Congo red Blue Red
   3.5−6.3 Gallein Orange Red
   3.8−5.4 Bromcresol green Yellow Blue
   4.0−5.8 2,5- Dinitrophenol Colorless Yellow
   4.2−4.6 Ethyl orange Colorless Yellow
   4.4−6.2 Methyl red Salmon Orange
   4.5−8.3 Litmus Red Blue
   4.8−6.2 Chlorphenol red Yellow Red
   5.1−6.5 Propyl red Pink Yellow
   5.4−6.8 Bromocresol purple Green-yellow Violet
   5.6−7.2 Alizarin Yellow Red
   6.0−7.6 Bromthymol blue Yellow Blue
   6.0−7.6 Bromoxylenol blue Orange-yellow Blue
   6.4−8.2 Phenol red Yellow Red-violet
   7.1−8.8 Cresol red Yellow Violet


5. 5−9.0 m-cresol purple Yellow Violet
   8.1−9.5 Thymol blue Yellow Blue
   8.3−10.0 Phenolphthalein Colorless Dark pink
   8.6−9.8 o-Cresolphthalein Colorless Pink

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