Skip to main content
Chemistry LibreTexts

Acid-Base Indicators

[ "article:topic-guide" ]
  • Page ID
    11840
  • The quantities listed in the "Preparation" column ought to be considered to be only good approximations. The audience of users, the decision whether to determine a titration error for a particular color change and the experimental environment must be considered when deciding what quantity is best to use. 
     

    Indicator pH Change Color Change Preparation
    Methyl Violet 0.0 - 1.6 yel to bl 0.01- 0.05 % in water
    Crystal Violet 0.0 - 1.8 yel to bl 0.02% in water
    Ethyl Violet 0.0 - 2.4 yel to bl 0.1 g in 50 ml of MeOH + 50 ml of water
    Malachite Green 0.2 - 1.8 yel to bl grn water
    Methyl Green 0.2 - 1.8 yel to bl 0.1% in water
    2 - (p - dimethylaminophenylazo)pyridine 0.2 - 1.8, 4.4 - 5.6 yel to bl, red to yel 0.1 % in ETOH
    o - Cresolsulfonephthalein (Cresol Red) 0.4 - 1.8, 7.0 - 8.8 yel to red, yel to red 0.1 g in 26.2 ml 0.01M NaOH + 223.8 ml water
    Quinaldine Red 1.0 - 2.2 col to red 1 % in ETOH
    p - (p - dimethylaminophenylazo) - benzoic acid, Na - salt (Paramethyl Red) 1.0 - 3.0 red to yel ETOH
    m - (p - anilnophenylazo)benzene sulfonic acid, Na - salt (Metanil Yellow) 1.2 - 2.4 red to yel 0.01% in water
    4 - Phenylazodiphenylamine 1.2 - 2.6 red to yel 0.01 g in 1 ml 1M HCI + 50 ml ETOH + 49 ml water
    Thymolsulfonephthalein (Thymol Blue) 1.2 - 2.8, 8.0 - 9.6 red to yel, yel to bl 0.1 g in 21.5 ml 0.01 M NaOH + 229.5 mL water
    m - Cresolsulfonephthalein (Metacresol Purple) 1.2 - 2.8, 7.4 - 9.0 red to yel, yel to purp 0.1 g in 26.2 ml 0.01M NaOH + 223.8 ml water
    p - (p - anilinophenylazo)benzenesulfonic acid, Na - salt (Orange IV) 1.4 - 2.8 red to yel 0.01 % in water
    4 - o - Tolylazo - o - toluidine 1.4 - 2.8 or to yel water
    Erythrosine, disodium salt 2.2 - 3.6 or,to red 0.1% in water
    Benzopurpurine 48 2.2 - 4.2 vt to red 0. 1 170 in water
    N,N - dimethyl - p - (m - tolylazo)aniline 2.6 - 4.8 red to yel 0.1% in water
    4,4' - Bix(2 - amino - l - naphthylazo)2,2' - stil - benedisulfonic acid 3.0 - 4.0 purp to red 0.1 g in 5.9 ml 0.05 M NaOH + 94.1 ml water
    Tetrabromophenolphthaleinethyl ester, K - salt 3.0 - 4.2 yel to bl 0.1 % in ETOH
    3',3",5',5" - tetrabromophenol - sulfonephthalein (Bromophenol Blue) 3.0 - 4.6 yel to bl 0.1 g in 14.9 ml 0.01M NaOH + 235.1 ml water
    2,4 - Dinitrophenol 2.8 - 4.0 colorless to yel saturated water solution
    N,N - Dimethyl - p - phenylazoaniline (p - Dimethylaminoazobenzene) 2.8 - 4.4 red to yel 0.1 g in 90 ml in ETOH + 10 ml water
    Congo Red 3.0 - 5.0 blue to red 0.1% in water
    Methyl Orange - Xylene Cyanole solution 3.2 - 4.2 purp to grn ready solution
    Methyl Orange 3.2 - 4.4 red to yel 0.01 % in water
    Ethyl Orange 3. 4 - 4. 8' red to yel 0.05 - 0.2% in water or aqueous ETOH
    4 - (4 - Dimethylamino - 1 - naphthylazo) - 3 - methoxybenzenesulfonic acid 3.5 - 4.8 vt to yel 0.1% in 60% ETOH
    3',3",5',5" - Tetrabromo - m - cresol - sulfonephthalein (Bromocresol Green) 3.8 - 5.4 yel to blue 0.1 g in 14.3 ml 0.01 M NaOH + 235.7 ml water
    Resazurin 3.8 - 6.4 or to vt water
    4 - Phenylazo - l - naphthylamine 4.0 - 5.6 red to yel 0.1 % in ETOH
    Ethyl Red 4.0 - 5.8 col to red 0.1 g in 50 ml MEOH + 50 ml water
    2 - (p - Dimethylaminophenylazo) - pyridine 0.2 - 1.8, 4.4 - 5.6 yel to red, red to yel 0.1 % in ETOH
    4 - (p - ethoxyphenylazo) - m - phenylene - diamine monohydrochloride 4.4 - 5.8 or to yel 0.1% in water
    Lacmoid 4.4 - 6.2 red to bl 0.2% in ETOH
    Alizarin Red S 4.6 - 6.0 yel to red 0.2 g in 100 mL of 1.5% HCl
    Methyl Red 4.8 - 6.0 red to yel 0.02 g in 60 ml ETOH + 40 ml water
    Propyl Red 4.8 - 6.6 red to yel ETOH
    5',5" - Dibromo - o - cresolsulfone - phthalein (Bromocresol Purple) 5.2 - 6.8 yel to purp 0.1 g in 18.5 ml 0.01M NaOH + 231.5 ml water
    3',3" - Dichlorophenolsulfonephthalein (Chlorophenol Red) 5.2 - 6.8 yel to red 0.1 g in 23.6 ml 0.01 M NaOH + 226.4 ml water
    p - Nitrophenol 5.4 - 6.6 col to yel 0.1% in water
    Alizarin 5.6 - 7.2, 11.0 - 12.4 yel to red, red to purp 0.1 % in MEOH
    2 - (2,4 - Dinitrophenylazo) - l - naphthol - 3, 6 - disulfonic acid, di - Na salt 6.0 - 7.0 yel to bl 0.1% in water
    3',3" - Dibromothymolsulfonephthalein (Bromothymol Blue) 6.0 - 7.6 yel to bl 0.1 gin 16 ml 0.01 M NaOH + 234 ml water
    6,8 - Dinitro - 2,4 - (lH)quinazolinedione (m - Dinitrobenzoylene urea) 6.4 - 8.0 col to yel 25 g in 115 ml M NaOH + 50 ml boiling water 0.292g of NaCl in 100 ml water
    Brilliant Yellow 6.6 - 7.8 yel to or 1 % in water
    Phenolsulfonephthalein (Phenol Red) 6.6 - 8.0 yel to red 0.1 gin 28.2 ml 0.01M NaOH + 221.8 ml water
    Neutral Red 6.8 - 8.0 red to amb 0.01 g in 50 ml ETOH + 50 ml water
    m - Nitrophenol 6.8 - 8.6 col to yel 0.3170 in water
    o - Cresolsulfonephthalein (Cresol Red) 0.0 - 1.0, 7.0 - 8.8 red to yel, yel to red 0.1 g in 26.2 ml 0.01 M NaOH + 223.8 ml water
    Curcumin 7.4 - 8.6, 10.2 - 11.8 yel to red ETOH
    m - Cresolsulfonephthalein (Metacresol Purple) 1.2 - 2.8, 7.4 - 9.0 red to yel, yel to purp 0.1 gin 26.2 ml 0.01M NaOH + 223.8 ml water
    4,4' - Bis(4 - amino - i - Daphthylazo) 2,2'stilbene disulfonic acid 8.0 - 9.0 bl to red 0.1 gin 5.9 ml 0.05 M NaOH + 94.1 ml water
    Thymolsulfonephthalein (Thymol Blue) 1.2 - 2.8, 8.0 - 9.6 red to yel 0.1 g in 21.5 ml 0.01 M NaOH + 228.5 ml water
    o - Cresolphthalein 8.2 - 9.8 col to red 0.04% in ETOH
    p - Naphtholbenzene 8.2 - 10.0 or to bl I % in dil. alkali
    Phenolphthalein 8.2 - 10.0 col to pink 0.05 gin 50 mL ETOH + 50 mL water
    Ethyl - bis (2.4 - dimethylphenyl)acetate 8.4 - 9.6 col to bl saturated solution in 50% acetone alcohol
    Thymolphthalein 9.4 - 10.6 col to bl 0.04 g in 50 ml ETOH + 50 ml water
    5 - (p - Nitrophenylazo)salicylic acid, Na - salt (Alizarin Yellow R) 10.1 - 12.0 yel to red 0.01 % in water
    p - (2,4 - Dihydroxyphenylazo)benzene - sulfonic acid, Na - salt 11.4 - 12.6 yel to or 0.1 % in water
    5,5' - Indigodisulfonic acid, di - Na - salt 11.4 - 13.0 bl to yel water
    2,4,6 - Trinitrotoluene 11.5 - 13.0 co] to or 0.1 - 0.5% in ETOH
    1,3,5 - Trinitrobenzene 12.0 - 14.0 col to or 0.1 - 0.5% in ETOH
    Clayton Yellow 12.2 - 13.2 yel to amb 0.1% in water