Sodium hydroxide titration with

Dissolve 1 g of sample, accurately weighed, in 50% ethanol/ water that previously has been neutralized to phenolphthalein TS with 0.1 A sodium hydroxide. Titrate with 0.5 N sodium hydroxide to a pink color. Each milliliter of titrant is equivalent to the amount of substance specified below. 

Dissolve 0-3 g in about 75 ml of water in a separator and add 0-4 ml of bromophenol blue test solution (0-1 g of bromophenol blue dissolved in 3 ml of 0 05N sodium hydroxide and diluted to 200 ml with water), 10 ml of chloroform and 1 ml of N sodium hydroxide. Titrate with 0-02M sodium tetraphenylboron to the disappearance of the blue colour from the chloroform layer, adding the titrant dropwise towards the end of the titration and shaking vigorously after each addition. 1 ml 0 02M = 0-008962 g C27H42O2NCI. 

Weak acid with a strong base. In the titration of a weak acid with a strong base, the shape of the curve will depend upon the concentration and the dissociation constant Ka of the acid. Thus in the neutralisation of acetic acid (Ka— 1.8 x 10-5) with sodium hydroxide solution, the salt (sodium acetate) which is formed during the first part of the titration tends to repress the ionisation of the acetic acid still present so that its conductance decreases. The rising salt concentration will, however, tend to produce an increase in conductance. In consequence of these opposing influences the titration curves may have minima, the position of which will depend upon the concentration and upon the strength of the weak acid. As the titration proceeds, a somewhat indefinite break will occur at the end point, and the graph will become linear after all the acid has been neutralised. Some curves for acetic acid-sodium hydroxide titrations are shown in Fig. 13.2(h) clearly it is not possible to fix an accurate end point. 

If desired, the cyclopentadienylsodium concentration in solution can be determined by withdrawing 1 ml. of solution, diluting this with 100 ml. of water, and titrating the resulting aqueous sodium hydroxide solution with 0.11V hydrochloric acid using methyl red as an indicator. 

Repeat problem 3, but compare the titration curves of 0.10 M sodium hydroxide with 0.10 M ammonium hydroxide titrated with 0.10 M hydrochloric acid. 

Congo red is an indicator that changes colour in the pH range 3.0 to 5.0. Suppose that you are titrating an aqueous sodium hydroxide solution with nitric acid added from a burette. Is congo red a suitable indicator If so, explain why. If not, will the end-point occur before or after the equivalence point Explain your answer. 

The a-naphthol is dissolved as described for j3-naphthol, and the solution is diluted and then precipitated with dilute acetic acid in the presence of 25 cc. 25 per cent sodium acetate solution. The coupling is carried out as with -naphthol, except that when the reaction for o-naphthol disappears, the solution is made alkaline with sodium hydroxide, reprecipitated with acetic acid, and the titration continued until the a-naphthol reaction again disappears. Frequently, as much as 30 per cent of the total volume of the diazonium solution is added in the second part of the titration, since so much of the naphthol is carried down by the dye. 

The concentration of the hydrogen iodide solution (usually 0.4—1.0 M) is determined by extracting the acid with deionized water and subsequently titrating the aqueous phase with 0.02 N standard sodium hydroxide solution with the aid of a pH meter. 

Lisinoprii can be determined by potentiometric titration with aqueous sodium hydroxide and non-aqueous perchioric acid. The sodium hydroxide titration is carried out by titrating the iisinoprii potentiometrically with carbonate free 0.1 N NaOH to one endpoint using a combination eiectrode. Lisinoprii can aiso be determined by titration potentiometricaiiy with 0.1 N perchloric acid in acetic acid to one endpoint. The electrode system consists of a glass electrode (such as a Metrohm Model EA 107 vs. a silver/silver chloride reference electrode such as a Metrohm Model EA 432 filled with 0.1 N lithium perchlorate in glacial acetic acid. 

Experiment 13. Add-base titration-. One possibility would be for example the titration of a sodium hydroxide solution with hydrochloric acid. A suitable sensor for these and other aqueous solutions would be a glass electrode that will be discussed in more detail in Sect. 22.7. 

Titration of Sodium Hydroxide Solution with Hydrochloric... 

Titration of Sodium Hydroxide Soiution with Hydrochioric Acid... 

Titrimetric methods Titrimetric assays have been developed for acesulfame-K (titrated with sodium methoxide in benzene), aspartame, sodium cyclamate, and sodium saccharin (titrated with perchloric acid), and for saccharin (acid form) with potassium hydroxide as titrant. Precipitation, chelatometric, and redox titrations are proposed for the determination of cyclamate. The oldest methods for saccharin involve its determination by means of a Kjeldahl procedure. 

Diblock copolymers were synthesised by two stepwise anionic polymerisation methods. One method produced diblock copolymer plus 30% of poly(2-vinylpyridine) homopolymer. The copolymers were dissolved in O.IM hydrochloric acid. When the pH was increased by the dropwise addition of 0.1 M sodium hydroxide, micelles with well-defined hydrodynamic diameters formed spontaneously at around pH 5. Further basification produced stable micelle structures and reacidification produced the mirror image of this titration curve. Blue swirls were observed when sodium hydroxide was added at pH4 or pH5. The micelle sizes were measured by quasielastic light scattering. It is shown that (1) it is possible to control micelUsation by pH and (2) formation of well-behaved micelles of variable hydrodynamic diameter is possible by titration of different ratios and different total polymer concentrations of poly(2-vinylpyridine/poly(2-vinylpyridine-block-PEO). Relevance to drug release systems that can remain intact and circulate for long periods within the vascular system is suggested. 17 refs. 

Add by pipette 25 ml 0.5 M sodium hydroxide. Titrate to phenolphtha-lein with the same solution. 

It turns out that amitriptyline and propranolol hydrochlorides can be titrated in a water/ethanol mixture with a 0.1 mol/L sodium hydroxide solution with a pH-metric equivalence point detection. Levomepromazine hydrochloride can be titrated in the same conditions but with propanol instead of ethanol as cosolvent. Propanol is preferred to ethanol because of the very high lipophilicity of the levomepromazine base. 

Therefore, the acid-base equilibrium is displaced toward the right. So, theophylline can be titrated by a sodium hydroxide solution with bromophenol blue as indicator. 

Both assayed by extraction of about 0-3 g of the base from sodium hydroxide solution with chloroform which is washed and evaporated. The residue is dissolved in excess of 0-lN hydrochloric acid and back-titrated with O IN sodium hydroxide to methyl red indicator. 1 ml 0-lN — 0-02467 g of the hydrochloride and 0-02733 g of the nitrate. 

To 10 ml of an approximately 5 per cent solution of phenazone add 90 ml of approximately 0 05N picric acid. Shake the mixture, leave overnight, filter and titrate 50 ml of the filtrate with 0-1N sodium hydroxide. Titrate 90 ml of the original picric acid solution with 0-1N sodium hydroxide, then subtract twice the former titration from this... 

Several finishing modes are applicable. The carbon dioxide can be retained in an absorption tube packed with Ascarite (sodium hydroxide mixed with asbestos) and weighed, or absorbed in a solution and titrated. The iodine produced in Eq. (14) can also be determined by titration. Alternatively, the iodine vapor can be led by a stream of nitrogen into an electrolysis cell, where iodine is reduced at controlled potential and the amount of electricity is recorded. Figure 6 shows, from right to left, the complete equipment for oxygen determination, which comprises the combustion train, the furnace for the oxidation of carbon monoxide, and the assembly for electrometric finish. 

The liberated iodine is titrated with standard sodium thiosulphate(Vr) solution after acidification to remove the hydroxide ions. 

Transfer 25 ml. of this dilute solution by means of a pipette to a conical flask, and add similarly 50 ml. of Ml 10 iodine solution. Now-add 10% sodium hydroxide solution until the liquid becomes pale yeilow in colour, and allow the solution to stand, with occasional shaking, at room temperature for at least 10 minutes. Then acidify with dilute hydrochloric acid (free from chlorine) in order to liberate the remaining iodine. Titrate the latter w ith Mho sodium thiosulphate solution, using starch as an indicator in the usual way. 

Weigh out accurately about 2 g. of glycine, transfer to a 250 ml. graduated flask, dissolve in distilled water, make up to the mark, and mix well. Transfer 25 ml. of the solution to a conical flask, add 2 drops of phenolphthalein, and then again add dilute sodium hydroxide very carefully until the solution is just faintly pink. No v add about 10 ml. (/. ., an excess) of the neutralised formaldehyde solution the pink colour of the phenolphthalein disappears immediately and the solution becomes markedly acid. Titrate with AI io sodium hydroxide solution until the pink colour is just restored. Repeat the process with at least two further quantities of 25 ml. of the glycine solution in order to obtain consistent readings. 

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