Acid-Base Indicators
Indicators Acid Colour       Range  Base Colour
Methyl Violet  yellow 0.0 - 1.6 blue
Malachite green  yellow 0.2 - 1.8 blue-green
Cresol red red 1.0 - 2.0 yellow
Thymol blue red 1.2 - 2.8 yellow
Benzopurpurin 4B violet 1.2 - 3.8 red
Orange IV red 1.4 - 2.6 yellow
Phloxine B colourless 2.1 - 4.1 pink
2,4-Dinitrophenol colourless 2.8 - 4.0 yellow
Methyl yellow (in ethanol)  red 2.9 - 4.0 yellow
Bromophenol blue yellow 3.0 - 4.6 blue-violet
Congo red  blue 3.1 - 4.9 red
Methyl orange red 3.2 - 4.4 yellow
Bromocresol green yellow 4.0 - 5.6 blue
alpha-Naphthyl red red 4.0 - 5.7 yellow
Methyl red red 4.8 - 6.0 yellow
Litmus (azolitmin)  red 5.0 - 7.0 blue
Bromocresol purple yellow 5.2 - 6.8 violet
4-Nitrophenol colourless 5.4 - 6.6 yellow
Bromothymol blue  yellow 6.0 - 7.6 blue
Phenol red  yellow  6.4 - 8.0 red
Brilliant yellow  yellow 6.6 - 7.9 orange
Cresol red yellow 7.0 - 8.0 red
Metacresol purple yellow 7.4 - 9.0 violet
2,6-Divanillyldenecyclohexanone yellow 7.8 - 9.4 red
Thymol blue  yellow 8.0 - 9.6 blue
Phenolphthalein colourless 8.3 - 10.0 dark pink
Thymolphthalein colourless 9.4 - 10.6 blue
Alizarin yellow R yellow 10.0 - 12.0 red
Malachite green hydrochloride green-blue 10.2 - 12.5 colourless
Methyl blue blue 10.6 - 13.4 pale-violet
Sodium indigosulphonate blue 11.4 - 13.0 yellow
Orange G yellow 11.5 - 14.0 pink
2,4,6-Trinitrotoluene colourless 11.7 - 12.8 orange
1,3,5-Trinitrobenzene colourless 12.0 - 14.0 orange