Indicators pH ranges

Ethyl bis-(2,4-dinitrophenyl) acetate (indicator) the stock solution is prepared by saturating a solution containing equal volumes of alcohol and acetone with the indicator pH range colorless 7.4-9.1 deep blue. This compound is available commercially. The preparation of this compound is described by Fehnel and Amstutz, Ind. Eng. Chem., Anal. Ed. 16 53 (1944), and by von Richter, Ber. 21 2470 (1888), who recommended it for the titration of orange- and red-colored solutions or dark oils in which the endpoint of phenol-phthalein is not easily visible. The indicator is an orange solid which after crystallization from benzene gives pale yellow crystals melting at 150-153.5°C, uncorrected. 

Indicator pH range Quantity to be used per 10 mL Colour in acid Colour in hase... 

Indicator pH range of eolor change Color change with Increasing pH... 

PROBLEM 16.17 The following acid-base indicators change color in the indicated pH ranges bromthymol blue (6.0—7.6), thymolphthalein (9.4-10.6), and alizarin yellow (10.1-12.0). Which indicator is best for the titration in Problem 16.16 Which indicator is unacceptable Explain. 

Indicator pH Range Acid Color Base Color... 

Indicator pH. range Colour in acid Colour in aljcalma... 

To obtain the indicator pH range, we take the negative logarithms of the two expressions ... 

Maximum adsorption (mmol kg at pH indicated). pH range over which maximum adsorption occurred. 

Name of Indicator pH range Colour in acid medium Colour in alkaline (moderate) medium... 

Types of Titration Examples of Reaction Suitable Indicator pH Range of Colour Change... 

The effect of pH on the polarization of iron is shown in Fig. 5.6. The effect ofpH on the polarization of type 304 stainless steel (nominally 18 to 20 wt% Cr, 8 to 10.5 wt%Ni, 0.08 wt% C maximum) in environments based on 1 M Na2SC>4 with additions of H2SO4 and NaOH to control the pH is shown in Fig. 5.31 (Ref 28). The influence of chromium and nickel in moving the anodic polarization curve of iron to lower current densities persists over the indicated pH range with the corrosion rates being very low for pH >4.0. 

COMMON INDICATORS Indicator pH Range Color Change... 

USE Manuf dyes, diamino phenol, etc wood preservative insecticide also as indicator. pH range 2.6 colorless, 4.4 yellow as a reagent for the detection of potassium and ammonium ions. 

USE Manuf dyes aud organic chemicals, as indicator- pH range 4.0 colorless, 5.4 yellow. 

Used as an acid-base indicator (pH range 10.0-11.6 colour change orange red). 

Used as 0.05% EtOH soln. as acid-base indicator (pH range 11.6-12.6 colour change pale yellow - red). Yellow needles (EtOH). Sol. H2O, EtOH, Et20. Mp 128°. 

Biological stain, indicator (pH range 12-14 colour change red colourless). Olive to dark olive green powder. Sol. H2O si. sol. EtOH. 

Dye, insecticide stabiliser, indicator. Used as ImM EtOH soln. for photometric detn. of Sn(/E) (e 200000), Zr (Amax 420 nm, s 63000) acid base indicator (pH range 2.0-4.0 colour change golden orange - yellow). 

Used as an acid-base indicator (pH range 6.5-8.5, colour change yellow blue). Pink cryst. powder. Sol. EtOH, bases insol. H2O. pK 7.6. 

Used as an aq. soln. as acid-base fluorescent indicator (pH range 3-4 colour change non fl.- blue pH range 10-12 colour change blue- yellow-green). Needles (H O). 

Used as 0.05% soln. in EtOH as acid-base fluorescent indicator (pH range 9.5-13.0, colour change dark blue - white/blue). Cryst. Mp 241°. p/C, 1.48 pA, 10.71 (25°). 

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