Several indicators that often were used in the identification

List of ph Acid-Base and metal ion titration Indicators

Amido black 10 B (redox)
dissolve 0.2 g in 100 ml of water
color change = yellowish-brown to blue
Alizarin
Dissolve 0.1g. in 100 ml. of 95% ethanol.
pH =10.1 – 12.1; color change = red to purple
Alizarin yellow
Dissolve 0.1g. in 100 ml. of water.
pH =10.0 – 12.1; color change = light yellow to brownish yellow
Alizarin sulphonic acid Na salt
Dissolve 0.1g. in 100 ml. water or in 100 ml 1:1 ethanol and water.
pH =4.3 – 6.3; color change = yellow to violet
Alkali blue
Dissolve 0.1g. in 100 ml. of 95% ethanol.
pH =9.4 – 14.0; color change = violet to pink

B

2.2′Bipyridin (iron(II) complex (redox)
dissolve 0.695 g of FeSO4.7H2O and 1.171 g of 2.2′-bipyridin in 100 ml of water
color change = pale blue to red
Brillant cresyl blue (redox)
dissolve 0.5 g in 100 ml of water or ethanol (96 %)
color change = blue to colorless
Brilliant green
Dissolve 0.1g. in 100 ml. of water.
pH =0.0 – 2.6; color change = yellow to green
Bromochlorophenol blue
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.69 ml of 0.1M sodium hydroxide and make up to 100 ml with water.
pH =3.0 – 4.6; color change = yellow to blue-violet
Bromocresol green
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.58 ml of 0.1Msodium hydroxide and make up to 100 ml with water.
pH =3.8 – 5.4; color change = yellow to blue
Bromocresol purple
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.4g in 0.74 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =5.2 – 6.8; color change = yellow to purple
Bromophenol blue
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.6 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =3.0 – 4.6; color change = yellow to blue-violet
Bromophenol red
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.94 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =5.2 – 6.8; color change = orange yellow to purple
Bromothymol blue
Dissolve 0.1g. in 100 ml. of 20% ethanol.
Bromo-oxylenol blue
Dissolve 0.1g. in 100 ml. of 95% ethanol.
pH =5.7 – 7.5; color change = orange yellow to blue

C

Cacotheline
saturated
color change = yellow to red-violet
Calcon or Solochrome Dark Blue (metal-ion EDTA)
sodium 1-(2- hydroxy-1-naphthylazo)-2-naphthol-4-sulphonate, Colour I ndex No.202; also called Eriochrome Blue Black R.
Dissolve 0.2g of the dyestuff in 50ml. of methanol.
The colour change is from pink to pure blue.
Calmagite
1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulphonic acid (IX) (metal-ion EDTA)
Can be substituted for Eriochrome Black T without change in the experimental procedures for calcium and magnesium.It has same colour change, which is clearer and sharper, and aqueous solutions of the indicator are almost stable indefinitely.
Dissolve 0.05g of calmagiite in 100ml. of water. The indicator is stable for at least 12 months when stored in a polythene bottle and in the dark.
Chlorophenol red
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.94 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =4.8 – 6.4; color change = yellow to purple
Congo red
Dissolve 0.2g. in 100 ml. of water.
pH =3.0 – 5.2; color change = blue to orange-yellow
Cresol purple
Dissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.86 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =7.4 – 9.0; color change = yellow to purple
Cresol red
Dissolve 0.1g. in 100 ml. of 50% ethanol, or dissolve 0.04g in 1.05 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =7.0 – 8.8; color change = yellow to purple
Cresol red
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 1.05 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =0.2 – 1.8; color change = red to yellow
m-Cresol purple
Dissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 1.05 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =1.2 – 2.8; color change = red to yellow
Crystal violet
Dissolve 0.1g. in 100 ml. of 70% ethanol.
pH =0.8 – 2.6; color change = yellow to blue-violet

D

Dibromopyrogallol sulphone phthalein (VIII) (metal-ion EDTA) or Bromopyrogallol Red
Dissolve 0.05g of the reagent in 100ml. of 50% ethanol.
The indicator is coloured orange-yellow in strongly acid solutions,; claret red in nearly neutral solutions; and violet to blue in basic solutions.
Dichlorofluorescein: (adsorption)
Dissolve 0.1g in 60 – 70 % ethanol, or
Dissolve 0.1g of dichlorofluoroceinate in 100ml water.
2.6-Dichlorophenolin-dophenol sodiumsalt (dihydrate) (redox)
dissolve 0.02 g in 100 ml of water
color change = blue to colorless
Di-iododimethylfluorescein:
(adsorption) Dissolve 1g in 70 5 ethanol.
4-(Dimethylamino) azobenzene
Dissolve 0.1 to 1.5 g. in 100 ml. of 90% ethanol.
pH =2.9 – 4.0; color change = red to yellow-orange
3.3′-Dimethylnahthidine(4.4′-Diamino-3.3-dimethyl-1.1′-binaphthaline) (redox)
dissolve 1.0 g in 100 ml of glacial acetic acid
color change = purple-red to colorless
N,N-Dimethyl-1.4-phenylenediammonium dichloride (redox)
dissolve 0.02 g in 100 ml of water
color change = dark-blue to colorless
2,5-Dinitrophenol
Dissolve 0.05 to 0.1g. in 100 ml. of 70% ethanol.
pH =4.0 – 5.8; color change = colorless to yellow
2,4-Dinitrophenol
Dissolve 0.1g. in 100 ml. of 70% ethanol.
pH =2.8 – 4.7; color change = colorless to yellow
Diphenylamine:
Dissolve 1g in 100 ml conc. H2SO4
color change = blue-violet to colorless
Diphenylamine-4-sulfonic acid barium salt (redox)
Dissolve 0.2g in 100 ml water
color change = red-violet to colorless
Diphenylamine-p-sulphonic acid (Na salt):
(redox) Dissolve 0.2g in 100 ml water.
Diphenylbenzidine:
(redox) Dissolve 1g in 100 ml conc.H2SO4
color change = violet to colorless
Diphenylcarbazide: (adsorption)
Dissolve 0.1g in 100 ml ethanol.
Diphenylcarbazone: (adsorption)
Dissolve 0.1g in 100 ml ethanol or iso-propyl alcohol.

E

Eosin bluish
Dissolve 0.1g. in 100 ml. of water.
pH =1.4 – 2.4; color change = colorless to pink fluorescence
Eosin: (adsorption)
Dssolve 0.1g in 100ml 70 % ethanol, or 0.1g of the sodium salt in 100 ml water.
Eosin yellowish
Dissolve 0.1g. in 100 ml. of water.
pH =0.0 – 3.0; color change = yellow to green fluorescence
Epsilon blue
Dissolve 0.1g. in 100 ml. of water.
pH =11.6 – 13.0; color change = orange to violet
Eriochrome Bkack T (metal-ion EDTA)
Sodium 1-(1-hydroxy-2-naphthalyzo)-6-nitro-2-naphthol-4-sulphonate (1); also known as Solochrome Black T or WDFA or No. 2 in the Colour Index. Not recommended for titration of solutions more acidic than Ph 6.5.
Dissolve 0.2 g of the dyestuff in 15ml. of ethanolamine and add 5ml of absolute ethanol to reduce the viscosity; the reagent is stable for several months.
A 0.4% solution of the pure dye in methanol may last for about a month.
Colour change is from blue to red.
Eriochrome Red B
sodium salt of 4-(2-hydroxy-4-sulpho-1-naphthylazo)-3-methyl-1-phenyl-2-pyrazolin-5-one (IX)—a pyrazolone azo-B-naphthol dyestuff. (metal-ion EDTA)
Dissolve 0.1g of the dyestuff in 50ml, ethanol. It is stable indefinitely.
The colour change from pink to pale yellow is almost instantaneous at about 80oC.
Erythrosin B
Dissolve 0.1g. in 100 ml. of water.
pH =0.0 – 3.6; color change = orange to red

F G H I J K L

Fast Sulphon Black F (metal ion EDTA)
Sodium salt of 1-hydrovy-8-(2-hydroxynaphthylazo)-2-(solphonaphtylazo)-3,6-disulphonic acid (V)
The indicator solution is 0.5% solution in water.
Specific colour change for copper is from magenta to pale blue to bright green.
Ferric indicator: (adsorption)
Use a saturated Ammonium Ferric sulphate soln. (~ 40%), add a few drops of 6M nitric acid, and use 1 ml for each titration.
Ferroin: (redox)
Make a 0.025M in water. or Dissolve 0.7g FeSO4.7H2O and 1.5g 1,10 o-phenanthroline in 100 ml water. color change = blue to orange-red
Fluorescein: (adsorption)
Dissolve 0.2g in 100 ml 70 % alcohol, or
Dissolve 0.2g of sodium fluorocienate in 100 ml water.
HHSNNA (metal-ion EDTA)
See Patton and Reeder’s
Indigo carmine
Dissolve 0.25g. in 100 ml. of 50% ethanol, or dissolve 1g in 100ml of water.
pH =11.5 – 13.0; color change = blue to yellow
Indigo carmine (Indigo disulfonate disodium salt) (redox)
Dissolve 0.5g in 100 ml water
color change = blue to yellowish
Litmus
Dissolve 4g. in 100 ml. of water.
pH =5.0 – 8.0; color change = red to blue
Note on Litmus:You can purify the commercial litmus as follows: Digest 10g. of the litmus with 35ml.of rectified spirit on a water bath for about 1 hr and decant the alcohol.; repeat this process twice. Extract the residue several times with water and allow to stand for several days. Decant or siphon off the clear extract. This is of suitable concentration for most purposes.
Bromo-cresol purple or Bromo-thymol blue are excellent substitutes for litmus.
Azolitmin is the pure litmus colouring matter. Dissolve 0.1g. in 100ml of water.

M

Malachite green oxalate
Dissolve 0.1g. in 100 ml. of water.
pH =0.0 – 2.0; color change = yellow to green-blue
N-Methlydiphenylamine-p-solphonic acid, (Na salt): (redox)
Dissolve 0.1g in 100 ml water.
Methylene blue (redox)
Dissolve 0.1 to 0.5g in 100 ml water
Methyl green
Dissolve 0.1g. in 100 ml. of water.
pH =0.1 – 2.3; color change = yellow to blue
Methyl orange
Dissolve 0.05g. of the sodium salt in 100 mls. of water, add 8 mls..of 0.1M hydrochloric acid, and filter if necessary, or
Dissolve 0.05g. of the free acid in 100 ml. water, and filter the solution if a precipitate forms.
pH =3.1 – 4.4; color change is pink/red towards yellow-orange
Screened methyl orange
Dissolve 1g. of methyl orange and 1.4g. of xylene cyanol FF in 200ml. water and make up to 500 ml. vol. with ethanol. The purpose of a screened or mixed indicator is to produce a more pronounced colour change at the end point. These types of indicators consist of either a mixture of two indicators or a mixture of an indicator and an inert dye. It changes colour at pH 3.8 — 4.1 from violet to green.
Methyl red
Dissolve 0.1g. of the Na salt in 100ml. of water, or dissolve in 30ml. of alcohol and dilute to 100ml. vol. with water.
pH =4.4 – 6.2; color change = red to yellow-orange
Methyl violet
Dissolve 0.1g. in 100 ml. of 20% ethanol.
pH =0.1 – 2.7; color change = yellow to violet
Methyl yellow Dissolve 0.1g. of the indicator in 100 ml of alcohol.
Mixed indicator
Dissolve 0.2g of methyl red and 0.1g of methyl blue or bromocresol green in 100 ml 95% ethanol
pH =4.3 – 5.2; color change = green to pink(ph 4.5)
Murexide (metal-ion EDTA)
This is the Ammonium salt of purpuric acid.
Suspend 0.5g of the powdered dyestuff in water, shake thoroughly and allow to settle. The saturated supernatant is used as the indicator.
The colour change is towards a blue endpoint.

N

1-Napltolphthalein
Dissolve 0.1g. in 100 ml. of 95% ethanol.
pH =7.1 – 8.3; color change = brownish to blue-green
Neutral red
Dissolve 0.3g. in 100 ml. of 70% ethanol.
pH =6.8 – 8.0; color change = blue-red to orange-yellow
Neutral red (redox)
Dissolve 0.5g in 100 ml of 95% ethanol
color change = violet-red to colorless
Nile blue (sulphate) (redox)
Dissolve 0.1g in 100 ml water
color change = blue-red to colorless
3-Nitrophenol
Dissolve 0.3g. in 100 ml. of 95% ethanol, or 0.08 g in 100 ml water.
pH =6.6 – 8.6; color change = colorless to yellow-orange
4-Nitrophenol
Dissolve 0.2g. in 100 ml. of 95% ethanol, or 0.08g in 100 ml water.
pH =5.4 – 6.8; color change = yellow to violet

O

P

Patton and Reeders indicator (metal-ion EDTA)
2-hydroxy-1-(2-hydroxy-4-sulpho-1-naphthylazo)-3-naphthoic acid (111)
Also known by the abbreviated name HHSNNA.
The dyestuff is thoroughly mixed with 100 times its weight of sodium sulphate, and 1g of this mix is used for each titration.
Used in the direct titration of calcium, particularly in the presence of magnesium, pH range 12-14.
A sharp colour change is obtained from wine red to pure blue.
Phenolphthalein
Dissolve 0.5 g. of the reagent in 50ml.of alcohol and add 50ml of water with stirring. Filter if a precipitate forms or
Dissolve 1g. of the dry indicator in 80 mls.ethylene glycol monoethyl ether (cellosolve) b.p.135oC, and dilute to 100ml. with distilled water.: the loss by evaporation is less by this preparation.
Phenol red
Dissolve 0.1g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 1.13 ml of 0.1M sodium hydroxide and make up to 100 ml.
pH =6.4 – 8.2; color change = yellow to red-violet
Pentamethoxytriphenyl carbinol
Dissolve 0.1 g in 100 ml of 95% ethanol
pH =1.2 – 3.2; color change = red to colorless
1.10-Phenanthroline (monohydrate) (redox)
Dissolve 0.695 g of FeSO4 x 7H2O and 1.487 g of 1.10-Phenanthroline in 100 ml of water
color change = pale-blue to red
N-Phenylanthranilic acid: (redox)
Dissolve 0.1 g in 5 ml of 0.1M sodium hydroxide and make up to 100 ml with water.
color change = purple-red to colorless
Picric acid
Dissolve 0.1 g in 100 ml of 20% ethanol
pH =0.2 – 1.0; color change = colorlass to yellow
Pyrocatechol Violet
Pyrocatechol sulphone phthalein (VII); Catechol violet. (metal-ion EDTA)
Dissolve 0.1g of the dyestuyy in 100ml.of water. This solution is stable for several weeks.
Colour change is progressive, from yellow yo blue to green.

Q R

S

Quinaldine red
Dissolve 0.1 g in 100 ml of 60% ethanol
pH =1.4 – 3.2; color change = colorless to pink
Rhodamine: (adsorption)
Dissolve 0.05 g in 100 ml water.
Safranin (redox)
Dissolve 0.5g in 100 ml water
color change = blue-violet(acidic),brown (alkaline) to colorless

T

4,5,6,7-Tetrabromo-phenolphthalein
Dissolve 0.1 g in 100 ml of 95% ethanol
pH =7.0 – 8.0; color change = colorless to purple
2.2′:6.2″-Terpyridine (iron(II) complex) (redox)
Dissolve 0.232 g FeSO4 x 7H2O and 0.389 g of 2.2′:6.2-terpyridine in 100 ml of water
color change = pale-blue to red
Tertrazine: (redox)
Dissolve 0.5g in water and use 4 drops per titration.
Thionine (redox)
Dissolve 0.5g in 100 ml of 95% ethanol
color change = violet to colorless
Titan yellow
Dissolve 0.1 g in 100 ml of 20% ethanol
pH =12.0 – 13.0; color change = yellow to red
Thymol blue
Dissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.86 ml of 0.1M sodium hydroxide and make up to 100 ml with water.
pH =8.0 – 9.6; color change = yellow to blue
Thymol blue
Dissolve 0.04g. in 100 ml. of 20% ethanol, or dissolve 0.04g in 0.86 ml of 0.1M sodium hydroxide and make up to 100 ml with water.
pH =1.2 – 2.8; color change = red to yellow
Thymolphthalein
Dissolve 0.1 g in 100 ml of 50% ethanol
pH =9.3 – 10.5; color change = yellow to red
Thymolphthalexone
Thymolphthalein complexone (metal-ion EDTA)
3,3-bis-[n,n-(carboxymethyl)aminomethyl] thymolphthalein (X)
Prepare a 0.5% solution in ethanol.alternatively, a finely ground mixture 1:100 with AR potassium nitrate may be used.
Blue to colourless or slight pink in alkaline medium.
Tropaeolin O
Dissolve 0.1g. of the solid in 100 ml of water.
Tropaeolin OO
Dissolve 0.1g. of the solid in 100 ml of water.
Universal indicator
Dissolve 0.04g of methyl red, 0.02g of methyl orange, 0.02g of phenolphthalein, 0.10g of thymol blue and 0.08g of bromothymol blue in 100 ml of 95% ethanol. Color change is red-orange-yellow-green (ph 7) –blue-indigo-violet.

U V W X Y Z

Variamine Blue B (metal-ion EDTA)
4-methoxy-4-amino-diphenylamine
The indicator solution is a 1% solution of the base in water. Ferric complex with EDTA – sharp change in redox potential – colourless to violet blue complex.
Variamine blue salt B (redox)
Dissolve 1.0 g in 100 ml of water or grind with sodium chloride or sodium sulfate anhydrous trituration
color change = blue-violet(acidic),yellow (alkaline) to colorless
p-Xylenol blue
Dissolve 0.1g. in 100 ml. of 50% ethanol, or dissolve 0.04g in 0.98 ml of 0.1M sodium hydroxide and make up to 100 ml with water.
pH =1.2 – 2.8; color change = red to yellow
p-Xylenol blue
Dissolve 0.1g. in 100 ml. of 50% ethanol, or dissolve 0.04g in 0.98 ml of 0.1M sodium hydroxide and make up to 100 ml with water.
pH =8.0 – 9.6; color change = yellow to blue
Xylenol Orange
3,3-bis[NN-di-(carboxymethyl)-aminomethyl]-o-cresolsulphonephthalein (VI)
Dissolve 0.5g of xylenol orange indicator in 100ml. of water) The solution is stable indeffinitely.
Acid solutions are coloured lemon yellow and those of the metal complexes intensely red.

EDTA INDICATORS

Bromopyrogallol Red
Dibromopyrogallol sulphone phthalein (VIII)
Dissolve 0.05g of the reagent in 100ml. of 50% ethanol.
The indicator is coloured orange-yellow in strongly acid solutions,; claret red in nearly neutral solutions; and violet to blue in basic solutions.
Calcon or Solochrome Dark Blue
sodium 1-(2- hydroxy-1-naphthylazo)-2-naphthol-4-sulphonate, Colour I ndex No.202; also called Eriochrome Blue Black R.
Dissolve 0.2g of the dyestuff in 50ml. of methanol.
The colour change is from pink to pure blue.
Calmagite
1-(1-hydroxy-4-methyl-2-phenylazo)-2-naphthol-4-sulphonic acid (IX)
Can be substituted for Eriochrome Black T without change in the experimental procedures for calcium and magnesium.It has same colour change, which is clearer and sharper, and aqueous solutions of the indicator are almost stable indefinitely.
Dissolve 0.05g of calmagiite in 100ml. of water. The indicator is stable for at least 12 months when stored in a polythene bottle and in the dark.
Eriochrome Bkack T
Sodium 1-(1-hydroxy-2-naphthalyzo)-6-nitro-2-naphthol-4-sulphonate (1); also known as Solochrome Black T or WDFA or No. 2 in the Colour Index. Not recommended for titration of solutions more acidic than Ph 6.5.
Dissolve 0.2 g of the dyestuff in 15ml. of ethanolamine and add 5ml of absolute ethanol to reduce the viscosity; the reagent is stable for several months.
A 0.4% solution of the pure dye in methanol may last for about a month.
Colour change is from blue to red.
Eriochrome Red B
sodium salt of 4-(2-hydroxy-4-sulpho-1-naphthylazo)-3-methyl-1-phenyl-2-pyrazolin-5-one (IX)—a pyrazolone azo-B-naphthol dyestuff.
Dissolve 0.1g of the dyestuff in 50ml, ethanol. It is stable indefinitely.
The colour change from pink to pale yellow is almost instantaneous at about 80oC.
Fast Sulphon Black F
Sodium salt of 1-hydrovy-8-(2-hydroxynaphthylazo)-2-(solphonaphtylazo)-3,6-disulphonic acid (V)
The indicator solution is 0.5% solution in water.
Specific colour change for copper is from magenta to pale blue to bright green.
HHSNNA
See Patton and Reeder’s
Murexide
This is the Ammonium salt of purpuric acid.
Suspend 0.5g of the powdered dyestuff in water, shake thoroughly and allow to settle. The saturated supernatant is used as the indicator.
The colour change is towards a blue endpoint.
Patton and Reeders indicator
2-hydroxy-1-(2-hydroxy-4-sulpho-1-naphthylazo)-3-naphthoic acid (111)
Also known by the abbreviated name HHSNNA.
The dyestuff is thoroughly mixed with 100 times its weight of sodium sulphate, and 1g of this mix is used for each titration.
Used in the direct titration of calcium, particularly in the presence of magnesium, pH range 12-14.
A sharp colour change is obtained from wine red to pure blue.
Pyrocatechol Violet
Pyrocatechol sulphone phthalein (VII); Catechol violet.
Dissolve 0.1g of the dyestuyy in 100ml.of water. This solution is stable for several weeks.
Colour change is progressive, from yellow yo blue to green.
Thymolphthalexone
Thymolphthalein complexone
3,3-bis-[n,n-(carboxymethyl)aminomethyl] thymolphthalein (X)
Prepare a 0.5% solution in ethanol.alternatively, a finely ground mixture 1:100 with AR potassium nitrate may be used.
Blue to colourless or slight pink in alkaline medium.
Variamine Blue B
4-methoxy-4-amino-diphenylamine
The indicator solution is a 1% solution of the base in water. Ferric complex with EDTA – sharp change in redox potential – colourless to violet blue complex.
Xylenol Orange
3,3-bis[NN-di-(carboxymethyl)-aminomethyl]-o-cresolsulphonephthalein (VI)
Dissolve 0.5g of xylenol orange indicator in 100ml. of water) The solution is stable indeffinitely.
Acid solutions are coloured lemon yellow and those of the metal complexes intensely red.

REDOX INDICATORS

Amido black 10 B
dissolve 0.2 g in 100 ml of water
color change = yellowish-brown to blue
2.2′Bipyridin (iron(II) complex
dissolve 0.695 g of FeSO4.7H2O and 1.171 g of 2.2′-bipyridin in 100 ml of water
color change = pale blue to red
Brillant cresyl blue
dissolve 0.5 g in 100 ml of water or ethanol (96 %)
color change = blue to colorless
2.6-Dichlorophenolin-dophenol sodiumsalt (dihydrate)
dissolve 0.02 g in 100 ml of water
color change = blue to colorless
3.3′-Dimethylnahthidine(4.4′-Diamino-3.3-dimethyl-1.1′-binaphthaline)
dissolve 1.0 g in 100 ml of glacial acetic acid
color change = purple-red to colorless
N,N-Dimethyl-1.4-phenylenediammonium dichloride
dissolve 0.02 g in 100 ml of water
color change = dark-blue to colorless
Diphenylamine:
Dissolve 1g in 100 ml conc. H2SO4
color change = blue-violet to colorless
Diphenylamine-4-sulfonic acid barium salt
Dissolve 0.2g in 100 ml water
color change = red-violet to colorless
Diphenylamine-p-sulphonic acid (Na salt):
Dissolve 0.2g in 100 ml water.
Diphenylbenzidine:
Dissolve 1g in 100 ml conc.H2SO4
color change = violet to colorless
Ferroin:
Make a 0.025M in water.
color change = blue to orange-red
Indigo carmine (Indigo disulfonate disodium salt)
Dissolve 0.5g in 100 ml water
color change = blue to yellowish
N-Methlydiphenylamine-p-solphonic acid, (Na salt):
Dissolve 0.1g in 100 ml water.
Methylene blue
Dissolve 0.1 to 0.5g in 100 ml water
color change = blue to colorless
Neutral red
Dissolve 0.5g in 100 ml of 95% ethanol
color change = violet-red to colorless
Nile blue (sulphate)
Dissolve 0.1g in 100 ml water
color change = blue-red to colorless
1.10-Phenanthroline (monohydrate)
Dissolve 0.695 g of FeSO4 x 7H2O and 1.487 g of 1.10-Phenanthroline in 100 ml of water
color change = pale-blue to red
N-Phenylanthranilic acid:
Dissolve 0.1 g in 5 ml of 0.1M sodium hydroxide and make up to 100 ml with water.
color change = purple-red to colorless
Safranin
Dissolve 0.5g in 100 ml water
color change = blue-violet(acidic),brown (alkaline) to colorless
2.2′:6.2″-Terpyridine (iron(II) complex)
Dissolve 0.232 g FeSO4 x 7H2O and 0.389 g of 2.2′:6.2-terpyridine in 100 ml of water
color change = pale-blue to red
Thionine
Dissolve 0.5g in 100 ml of 95% ethanol
color change = violet to colorless
Variamine blue salt B
Dissolve 1.0 g in 100 ml of water or grind with sodium chloride or sodium sulfate anhydrous trituration
color change = blue-violet(acidic),yellow (alkaline) to colorless

ADSORPTION INDICATORS

Bromo-phenol blue:
Dissolve 0.1g in distilled water.
Dichlorofluorescein:
Dissolve 0.1g in 60 – 70 % ethanol, or
Dissolve 0.1g of dichlorofluoroceinate in 100ml water.
Diphenylamine;Dissolve 1g in 100 ml conc. sulphuric acid
Di-iododimethylfluorescein:
Dissolve 1g in 70 5 ethanol.
Diphenylcarbazide:
Dissolve 0.1g in 100 ml ethanol.
Diphenylcarbazone:
Dissolve 0.1g in 100 ml ethanol or iso-propyl alcohol.
Eosin:
Dssolve 0.1g in 100ml 70 % ethanol, or 0.1g of the sodium salt in 100 ml water.
Ferric indicator:
Use a saturated Ammonium Ferric sulphate soln. (~ 40%), add a few drops of 6M nitric acid, and use 1 ml for each titration.
Fluorescein:
Dissolve 0.2g in 100 ml 70 % alcohol, or
Dissolve 0.2g of sodium fluorocienate in 100 ml water.
Rhodamine:
Dissolve 0.05 g in 100 ml water.
Tertrazine:
Dissolve 0.5g in water and use 4 drops per titration.

                                                     General reagents

Ammonium acetate.
Dissolve 231 g of the salt in 1 liter of water. (3M)
Ammonium carbonate.
The commercial salt is a mixture of bicarbonate and carbamate. Dissolve 192 g of the salt in a mixture of 140ml conc. ammonia solution and water to make up 1 liter of solution. (2M)
Ammonium chloride
dissolve 169 g of the salt in 1 liter of solution (3M).
Ammonium nitrate
dissolve 80 g of the salt in 1 liter of water. (1M)
Ammonium oxalate
dissolve 71 g of the crystaline salt in 1 liter of water.(0.5M)
Ammonium sulphate
dissolve 132 g of the salt in 1 liter of water.(1M)
Ammonium sulphide
use the yellow commercial product
Ammonium thiocyanate
Dissolve38 g of the salt in 1 liter of water (0.5M)
Barium chloride
dissolve 61 g of the salt in 1liter of water.(0.25M)
Bismuth chloride
dissolve 53 g of the salt in a solution of 800mls water and 200mls conc. HCl.(0.17M)
Bismuth nitrate
dissolve 40g of the salt in 800mls water and 200mls conc. nitric acid.(0.08M)
Bromine water
a saturated aqueous solution is prepared by shaking 35g or 11ml liquid bromine with 100ml water. Add more bromine if necessary to a slight excess.
Calcium chloride
dissolve 55 g of the hydrated salt in 1 liter of water (0.25M)
Calcium sulphate
shake 3 g of the salt with 1 liter of water, filter and decant the saturatrd solution after several hours (0.015M)
Chlorine water
saturate 250ml of water with chlorine. The chlorine may be prepared by dropping conc. HCl upon KmnO4. Preserve in a dark coloured bottle.(6.8g/l)
Cobalt nitrate
dissolve 44 g of the salt in 1 liter of water. (0.15M)
Copper sulphate
dissolve 125 g of the salt in 1 liter of water, and add 5mls of conc. Sulphuric acid.(0.5M)
Ferric chloride
dissolve 135 g of the hydrated salt in 1 liter of water containing 20mls of conc. HCl (0.5M)
Ferrous sulphate
dissolve 140 g of the salt in 1 liter of water, containing 7 ml of conc. Sulphuric acid (0.5M)
Hydrogen sulphide
H2S generated from a Kipps apparatus ( ~42g/l)
Iodine solution
dissolve 12.7 g of iodine in a solution of 20g of pure KI in 30 ml of water, and dilute to 1 liter with water.(0.05m)
Lead acetate
dissolve 95 g of the salt in 1 liter of water (0.25M)
Lime water
saturate 2 g of Ca(OH)₂ in 1 liter of water. Filter and protect ffom CO₂ of the air. (0.02M)
Magnesium sulphate
dissolve 62 g of the salt in 1 liter of water (0.25M)
Magneson (4-(4-nitrophenylazo) resorcinol
0.001% in 1M NaOH.
Mercuric chloride
dissolve 27 g of the salt in 1 liter of water (0.1M)
Mercurous nitrate
dissolve 25g of the salt in 500ml water and add 25mls conc. nitric acid.
Potassium antimonate
make a solution of 22 g of the salt in 1liter of water, boil to almost fully dissolved, cool immediately and add 35ml of 10% KI. Leave overnight, then filter.(0.25M)
Potassium chromate
dissolve 49g of the salt in 1 liter of water (0.25M)
Potassium ferricyanide
dissolve 55 g of the salt in 1 liter of water (0.25M)
Potassium ferrocyanide
dissolve 53 g of the salt in 1 liter of water (0.125M)
Potassium iodide
dissolve 83 g of the salt in 1 liter of water (0.5M)
Potassium permanganate
dissolve 3.2g of the salt in hot water, dilute to 1 liter, and filter through glass wool (0.01M)
Potassium thiocyanate
dissolve 49g of the salt in 1 liter of water (0.25M)
Silver nitrate
dissolve 17g of the salt in 1 liter of water (0.1M)
Silver sulphate
dissolve 8g of the salt in 1 liter of water. this is nearly a saturated solution (0.025M)
Sodium acetate
dissolve 408g of the crystaline salt in 1 liter of water (3M)
Sodium carbonate
dissolve 430g of the crystaline salt in 1 liter of water (1.5M)
Sodium cobaltinitrite
1. dissolve 25g of NaNO₂ in 75 ml water, add 2ml glacial acetic acid and then 2.5gm of Co(NO₃.6H₂O. Allow to stand for a few days, filter and dilute to 100ml. (0.08M)
2. dissolve 17g of the pure salt in 250ml water.
Disodium hydrogen phosphate
dissolve 120g of the salt in 1 liter of water 0.34M)
Stannous chloride
dissolve with heat 56g of the salt in 100ml conc. HCl and dilute to 1 liter. Keep a few pieces of granulated zinc in the stored solution to avoid oxidation. (0.25M)
Thiourea
dissolve 10g in 100ml of water (10%)
Titan yellow
dissolve 1g in 100ml of water (1%)
Zinc nitrate
dissolve 150g of the salt in 1 liter of water (0.5M)

Concentrated Acids

Dilute Acids

Acetic Acid
Dilute 116 mls.of the concentrated acid to 1 litre of water. (2M)
Hydrochloric Acid
Dilute 172 mls. of the concentrated acid to 1 litre with water.(2M)
Nitric Acid
Dilute 122mls. of the concentrated acid to 1 liter with water. (2M)
Sulphuric Acid
Pour 56 mls.of the concentrated acid slowly and with constant stirring into about 500mls. of water, cool, and dilute to 1 litre. (1M)
Sulphurous Acid
Prepare a saturated solution of SO₂ gas in water. (6-7%) by weght.

Dilute Bases

Ammonia solution conc.
The commercial product, S.G. 0.88 contains about 28% NH₃. (15M)
Ammonia solution dilute
Dilute 335 ml of the commercial solution to 1 liter (5N)
Barium hydroxide
Shake 70 gms. of crystalised salt in 1 liter of water. Filter or siphon off the liquid , and protect from CO₂ of the air. Use a CaCl₂ Guard tube. (0.2M)
Calcium hydroxide (Lime water)
Shake 2-3 gms. of calcium hydroxide with 1 liter of water. Filter or siphon off liquid, and protect from CO₂ of the air. Use a CaCl₂ Guard tube. (0.02M)
Potassium hydroxide
Dissolve 112 gms. of KOH pellets in water , and dilute to 1 liter. (2M)
Sodium hydroxide
Dissolve 200 gm pellets in water and dilute to 1 liter. (5M)

Store in stoppered polythene bottles

Aluminium
Dissolve 1.000 g of Aluminium metal in 25ml. of hydrochloric acid (S.G. 1.18) and a few drops of nitric acid (S.G. 1.42) Dilute to 1 litre in a volumetric flask with deionised water.

Antimony
Dissolve 1.000g antimony in 10ml. conc. hydrochloric acid, a few drops of conc. nitric acid, and 10g of tartaric acid. Dilute to 1 litre..
Arsenic
Dissolve 1.000g of arsenic powder in 50ml. conc. nitric acid. Dilute to 1 litre with deionised water or
Dissolve 1.3200g arsenous oxide (As₂O₃) , dried to 110°C, in 50ml. of conc. hydrochloric acid. Dilute to 1 litre with deionised water.
Barium
Dissolve 1.4380g.of barium carbonate (BaCO₃) in 20ml. 1M hydrochloric acid. Dilute to 1litre in a volumetric flask with deionised water.
Beryllium
Dissolve 19.639g. of beryllium sulphate (BeSO₄) in 250 deionised water. Dilute to 1 litre in a volumetric flask with deionised water.
Bismuth
Dissolve 1.000g. of bismuth metal in 50ml. conc. nitric acid Dilute to 1litre in a volumetric flask with deionised water.
Dissolve 1.1148g. of bismuth trioxide (Bi₂O₃) in the minimum quantity of comc. hydrochloric acid. Dilute to 1litre in a volumetric flask with deionised water.
Boron
Dissolve 5.1744g. of boric acid (H₃BO₃) in 500ml. of deionised water. Dilute to 1litre in a volumetric flask with deionised water..
Cadmium
Dissolve 1.000g. of cadmium metal in 20ml. of 5M.hydrochloric acid and 2 drops of conc. nitric acid. Dilute to 1litre.
Dissolve 2.0360g. of cadmium chloride in 250 ml deionised water.Dilute to 1 litre in a volumetric flask.
Dissolve 2.1032g. of cadmium nitrate in 250ml.of deionised water. Diluteto1 litre in a volumetric flask.
Caesium
Dissolve 1.2670g. of caesium chloride (CsCl) in 100ml. of deionised water. Dilute to 1litre in a volumetric flask with deionised water.
Calcium
Dissolve 2.4973g. of calcium carbonate (CaCO₃) in 25ml. of 1M hydrochloric acid. This should be added dropwise to avoid losses during the vigorous effervescence. Dilute to 1litre in a volumetric flask with deionised water.
Dissolve 2.7693g. of calcium chloride (CaCl₂) in 100ml. deionised water. Dilute to 1litre in a volumetric flask with deionised water.
ChromiumCobalt
Dissolve 1.000g. of cobalt metal in 50ml. of 5M hydrochloric acid. Dilute to 1litre in a volumetric flask with deionised water.or
Dissolve 4.9379g. of cobalt nitrate (Co(NO3)₂.6H2O in 250 ml. deionised water. Dilute to 1litre in a volumetric flask with deionised water.
Dissolve 4.0380g. of cobalt (11) chloride (CoCl₂.6H2O) in 200ml. deionised water. Dilute to 1litre in a volumetric flask with deionised water.
Copper
Dissolve 1.000g. of copper metal in 50ml. of 5M nitric acid. Dilute to 1 litre in a volumetric flask wih deionised water. or
Dissolve 3.7980g. of (Cu(NO3)₂.3H2O in 250ml. of deionised water. Dilute to 1 litre in a volumetric flask wih deionised water.
Gold
Dissolve 1.000g. of gold metal in 15ml. of conc. hydrochloric acid and 5ml. of conc. nitric acid. Dilute to 1 litre in a volumetric flask wih deionised water.or
Dissolve 1.8110g. of ammonium chloroaurate (NH₄AuCl₄) in 100ml.of deionised water. Dilute to 1 litre in a volumetric flask wih deionised water.
Iron
Dissolve 1.000g. of iron wire or granules in 20ml. of 5M hydrochloric acid Dilute to 1 litre in a volumetric flask wih deionised water.or
Dissolve 4.8400g. of iron (111) chloride (FeCl₃.6H2O) in 200ml. of deionised water. Dilute to 1 litre in a volumetric flask wih deionised.water
Lanthanum
Dissolve 1.1782g. of lanthanum oxide (La₂O₃) in 20ml. of 5M hydrochloric acid. Dilute to 1 litre in a volumetric flask wih deionised water.
Lead
Dissolve 1.000g.of lead metal in 50ml. of 2M nitric acid. Dilute to 1 litre in a volumetric flask with deionised water.
Dissolve1.5980g. of lead nitrate ( Pb(NO₃)₂ ) in 100ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water.
Magnesium
Dissolve 1.000g. of magnesium metal in 50ml. of 5M hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water.or
Dissolve 3.9160g. of magnesium chloride (MgCl₂.6H2O) in 200ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water.
Manganese
Dissolve 1.000g. of manganese metal in50ml. of conc. hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water.
Dissolve 3.6077g. of manganesse chloride (MnCl₂.4H20) in 50ml. conc. hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water.
Mercury
Dissolve 1.000g. of mercury metal in20ml. of 5M nitric acid. Dilute to 1 litre in a volumetric flask with deionised water.or
Dissolve 1.3520g. of mercury (11) chloride (HgCl₂) in 250ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water. orDissolve 1 .0800g. of mercury (11) oxide (HgO) in 20ml. of 5M hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water.

Molybdenum
Dissolve 1.000g. of molybdenum powder in 10 ml. of conc. hydrochloric acid and 10ml. of deionised water. Add 1ml. of conc.nitric acid. Use a magnetic stirrer to completely dissolve the molybdenum. Dilute to 1 litre in a volumetric flask with deionised water. or
Dissolve 1.8403g. of ammonium molybdate (NH₄)₆MO₇O₂₂.4H2O in 500ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water. or
Dissolve 1.5000g. of molybdenum trioxide (MoO₃) in 25ml. conc. hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water.
Nickel
Dissolve 1.000g. of nickel in 20ml. of conc. nitric acid. Dilute to 1 litre in a volumetric flask with deionised water.or
Dissolve 4.9530g. of nickel nitrate (Ni(NO₃)₂.6H2O) in 1 litre volumetric flask with deionised water.
Potassium
Dissolve1 1.9070 g. of dry potassium chloride in 250 ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water.
Silica
Dissolve about 7.6 g. of sodium metasilicate (Na₂SiO₃.5H2O in deionised water. Dilute to 1 litre in a volumetric flask with deionised water.
Silver
Dissolve 1.5750 of silver nitrate in 200ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water.
Sodium
Dissolve 2.5420g. of sodium chloride (NaCl) in 200ml. of deionised water. Dilute to 1 litre in a volumetric flask.
Strontium
Dissolve 2.4150g. of strontium nitrate (Sr(NO₃)₂ in 200ml. of deionised water. Dilute to 1 litre in a volumetric flask with water.
Tin
Dissolve 1.000g. of tin metal in 200ml. of conc. hydrochloric acid and 5ml. of conc.nitric acid. Dilute to 1 litre in a volumetric flask with deionised water. or
Dissolve 2.9540 of tin (1V) chloride pentachloride (SnCl₄.5H2O) in 500ml. deionised water.If precipitate forms, redissolve by adding 6M hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water
Uranium
Dissolve 21.100g. of uranyl nitrate (UO₂(NO₃)₂6H₂O) in 250ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water.or
Dissolve 14.329g. of uranyl chloride (UO₂Cl₂) in 250ml. of deionised water. Dilute to 1 litre in a volumetric flask with deionised water.
Vanadium
Dissolve 1.000g. of vanadium metal in 25ml.conc.nitric acid. Dilute to 1 litre.
Dissolve 2.2960g. of ammonium metavanadate (NH₄VO₃) in 20ml. of 100 volume hydrogen peroxide. Dilute to 1 litre in a volumetric flask with deionised water.
Zinc
Dissolve 1.000g. of zinc metal in 30ml. of 5M hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water.orDissolve 1.2450g. of zinc oxide (ZnO) in 5ml of deionised water followed by 25ml. of 5M hydrochloric acid. Dilute to 1 litre in a volumetric flask with deionised water

Zirconium
Dissolve 1.000g. of zirconium metal in 25ml. of hydrofluoric acid (40% w / v) in a P.T.F.E. beaker. Dilute to 1 litre in a polpropylene volumetric flask with deionised water
or
Dissolve 3.7174g. of dry zirconium nitrate in 1 litre deionised water

Dissolve 7.6960g. of chromium nitrate (Cr(NO3)₃.9H2O) in 250ml.of deionised water. Dilute to 1litre in a vol. Flask.

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