Xylenol orange indicator

Xylenol orange indicator. Finely grind (triturate) 0.20 g of the solid dyestuff with 50 g of potassium chloride (or nitrate). This solid mixture is used because solutions of xylenol orange are not very stable. 

Fluoride may be determined by precipitation as lead chlorofluoride, the precipitate being dissolved in dilute nitric acid and, after adjusting the pH to 5-6, the lead is titrated with EDTA using xylenol orange indicator.10... 

Procedure. Prepare a standard solution of lead nitrate (0.05M), a 0.05 per cent aqueous solution of xylenol orange indicator, and a 1,10-phenanthroline solution (0.05M) by dissolving 0.90 g of pure 1,10-phenanthroline in 1.5 mL of concentrated nitric acid and 100 mL of water. 

Into a conical flask, pipette a 50.0 or 100.0 mL aliquot of the solution and adjust the pH to 1-2 with aqueous ammonia solution (use pH test-paper). Add five drops of xylenol orange indicator and titrate with additional 0.05 M EDTA until the colour changes sharply from red to yellow. This gives the bismuth content. Record the total (combined) volume of EDTA solution used. Now add small amounts of hexamine (ca 5g) until an intense red-violet coloration persists, and titrate with the standard EDTA to a yellow end point the further consumption of EDTA corresponds to the lead-plus-cadmium content. 

Ni2+ can be analyzed by a back titration by using standard Zn2+ at pH 5.5 with xylenol orange indicator. A solution containing 25.00 mL of Ni2+ in dilute HCI is treated with 25.00 mL of 0.052 83 M Na2EDTA. The solution is neutralized with NaOH, and the pH is adjusted to 5.5 with acetate buffer. The solution turns yellow when a few drops of indicator are added. Titration with 0.022 99 M Zn2+ requires 17.61 mL to reach the red end point. What is the molarity of Ni2+ in the unknown ... 

Issa et al. [9] used various metal ions for the volumetric determination of mefenamic acid. Mefenamic acid was precipitated from its neutral alcoholic solution by a standard solution of either silver nitrate, mercurous acetate, or potassium aluminum sulfate. In the argentimetric procedure, residual Ag(I) was titrated with standard NH4SCN. With Hg(OAc)2 or potash alum, the residual metal was determined by adding EDTA and conducting back titration of excess of EDTA with standard Pb(N03)2 using xylenol orange indicator. The applied methods were used for the determination in bulk drug substance, and in its formulations. 

The composition of the THF complexes of the lanthanide trichlorides is established by dissolution of a weighed amount of each compound in water and determination of chloride potentiometrically with aqueous silver nitrate. Analysis for the lanthanide is effected by titration with disodium ethylenediaminetetraacetate using xylenol orange indicator after appropriate buffering of the solution.The IR spectra of all the trichlorides show intense bands at 1020 and 880 cm" (see below), indicative of coordinated THF. ... 

Materials. Solutions of Eu, Th, and U were made by dissolving known amounts of the metal oxides in nitric or perchloric acid. The europium solution was standardized by titration with EDTA using xylenol orange indicator at pH 5.2. 

The oxidation of the hydrazinium ion by Tl + probably involves substitution of hydrazine for water in the hydrated thallium(iii) species. The kinetics of complex formation between thallium(iii) and 4-(2-pyridylazo)resorcinol in aqueous solutions have been studied. Two pathways have been identified, involving Tl and [T10H] + reacting with the protonated ligand. The similarity in rate to that of the corresponding reaction of thallium(iii) with Semi-xylenol Orange indicates that the rate is controlled by loss of water from the hydrated thallium cation. ... 

For zinc, to 10 ml of the lotion add 10 ml of a 10 per cent v/v solution of thioglycerol in water and, when precipitation is complete, add 2 ml of dilute hydrochloric acid and 3 g of hexamine, whereupon the precipitate redissolves. Allow to stand for fifteen minutes, add 4 drops of xylenol orange indicator solution and titrate with 0 05M EDTA to the bright yellow colour of the indicator. 1 ml 0 05M EDTA = 0 01438 g ZnS04,7H20. 

Dissolve about 0 08 g of sodium fluoride, accurately weighed, in about 30 ml of water and add 15 ml of 0-2N sodium chloride followed by 20 ml of 95 per cent ethanol. Heat the solution until it is just boiling and then add, with stirring, exactly 50 ml of 0-05M lead nitrate solution this addition should be made dropwise at first and then more rapidly. Heat further to coagulate the precipitate and allow the mixture to cool to room temperature. Filter the mixture and wash the precipitate three times with small quantities of 20 per cent ethanol. To the combined filtrate and washings add 1 g hexamine and a few drops of xylenol orange indicator solution and titrate with 0 05M EDTA to the yellow end-point 1 ml 0-05M lead nitrate = 0 0021 g NaF. 

To a solution containing about 0 08 g of zinc at a pH of approximately 6 0 add 3 g of hexamine followed by 4 drops of xylenol orange indicator and titrate with 0-05M EDTA to the bright yellow colour. 

The aluminium is determined on a 10-ml aliquot of the acid solution prepared above as follows Neutralise to Congo red paper with 20 per cent sodium hydroxide, add 40 ml of 0 05M EDTA and warm on a water-bath for thirty minutes. Cool, add about 3 g of hexamine and titrate with 0 IN zinc solution to the purple-red end-point of xylenol orange indicator. From the ml 0 05M EDTA absorbed subtract half the ml required in the zinc determination. 1 ml 0 05M EDTA (remainder) - 0 001349 g Al. 

Lead(II) ions in aqueous solution can be titrated with EDTA solution using xylenol orange indicator and hexamine to control the pH. They can be precipitated as chromate which may be weighed or it may be dissolved in dil. HCI, adding excess KI and titrating... 

Prepare 0.05 M solution of purest cadmium sulphate or nitrate. Pipette 25.0 cm, dilute widi 50 cm of water and add 3 drops of xylenol orange indicator and then one drop of dilute sulphuric acid to turn the colour to yellow. Then introduce powdered hexamine with agitation until the colour is clearly red. Alternatively add a 15% solution of... 

Xylenol orange indicator dissolve 0.5 g in 100 cm water P II) reacts with EDTA in a 1 1 molar ratio If volume of EDTA is V cm, number of mols EDTA=... 

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