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
- 0−2.8 Thymol blue Red Yellow
- 2−4.0 Benzopurpurin Violet Red
- 3−3.0 Orange IV Red Yellow
- 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 - 5−9.0 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
8684-X AppB.F 2/9/01 8:28 AM Page 391