Hydrochloric acid titration with sodium

The preparation of cyclohexylmagnesium bromide is described on p. 22. The solution may be standardized by titrating against 0.5 N hydrochloric acid, and exactly one mole equivalent is used in the preparation. Five cubic centimeters of cyclohexylmagnesium bromide solution is slowly added to 20 cc. of water, an excess of the standard acid is added, and the excess acid titrated with sodium hydroxide. If 85 g. (3.5 moles) of magnesium, one liter of dry ether, and 571 g. of cyclohexyl bromide (3.5 moles) are used, a solution results which is about 2 molar. 

A method involving electrometric titration depends on the volumetric reduction of selenious acid to selenium by means of titanium sulphate. The method is rapid and accurate5 if the solution is in cold concentrated hydrochloric acid saturated with sodium chloride. The presence of the latter is important, for it ensures rapid and uniform coagulation of the selenium hydrosol and increases the sharpness in the change of voltage at the end-point. The use of the hydrochloric acid in the cold eliminates the otherwise almost inevitable loss of selenium by volatilisation. Under these conditions any tellurium which may be present is unreduced and only has the effect of modifying the nature of the end-point.6... 

One of the most common titrations of this type is the titration of hydrochloric acid, HC1, with sodium hydroxide, NaOH. If you remember from earlier, this is a neutralization reaction. However, you should also remember from earlier that in order for a complete neutralization to occur, the reaction must use appropriate stoichiometric ratios. When we first look at the process, we will do so with two solutions of known concentration, but you will see that this process can be used to determine the concentration of one of the solutions. 

The analysis of mixtures of these two acids is very simple. The mixture is first titrated with nitrite to determine the total of the two acids, and then the 2,5,7 acid is titrated with sodium hypobromite. The 2,5,7 add reacts smoothly in hydrochloric acid solution with sodium hypobromite, taking up two atoms of bromine, while the 2,6,8 acid is entirely unreactive. This behavior is surprisingly similar to that of Schaeffer salt and R salt. 

Two methods which are quite widely applicable to many local anaesthetics are non-aqueous titration (perchloric acid to crystal violet, p. 792) and titration with sodium nitrite (0 5 g in 75 ml water and 10 ml hydrochloric acid, titrating with O IM nitrite and determining the end-point using the dead-stop technique, p. 867). A few materials such as benzocaine may be determined by both methods but in most cases either one or the other is applicable. Lignocaine hydrochloride, for example, gives a satisfactory end-point by the non-aqueous method but cannot be determined by titration with nitrite procaine hydrochloride on the other hand is satisfactorily titrated wdth nitrite but gives rise to a precipitate during titration in non-aqueous medium which obscures the end-point. Certain compounds such as amethocaine hydrochloride cannot be determined by either method. 

Dilute 50 ml of syrup to 400 ml, precipitate with sodium hydroxide and a little bromine water, to oxidise any iron in the ferrous state. Bring the mixture to the boil and allow the precipitate to settle. After filtration on paper in a Gooch crucible, dissolve the precipitate in hydrochloric acid, reprecipitate with sodium hydroxide and redissolve in hydrochloric acid. Add potassium iodide and titrate with 0 1 N thiosulphate. 1 ml = 0 005585 g Fe. 

Alternatively, a known weight of the pyrolusite may be heated with concentrated hydrochloric acid and the chlorine evolved passed into potassium iodide solution. The iodine liberated is titrated with sodium thiosulphate ... 

Reduction. Triaryknethane dyes are reduced readily to leuco bases with a variety of reagents, including sodium hydrosulfite, 2inc and acid (hydrochloric, acetic), 2inc dust and ammonia, and titanous chloride in concentrated hydrochloric acid. Reduction with titanium trichloride (Knecht method) is used for rapidly assaying triaryknethane dyes. The TiCl titration is carried out to a colorless end point which is usually very sharp (see Titanium COMPOUNDS, inorganic). 

Procedures have also been devised for the determination of metallic constituents. Thus, mercury is absorbed in nitric acid and titrated with sodium diethyldithiocarbamate, whilst zinc is absorbed in hydrochloric acid and determined by an EDTA titration (see Section 10.65). 

Various workers have discussed the determination of total alkalinity and carbonate [ 10-12], and the carbonate bicarbonate ratio [ 12] in seawater. A typical method utilises an autoanalyser. Total alkalinity (T milliequivelents per litre) is found by adding a known (excess) amount of hydrochloric acid and back titrating with sodium hydroxide solution a pH meter records directly and after differentiation is used to indicate the end-point. Total carbon dioxide (C milliequivelents per litre of HCO3 per litre) is determined by mixing the sample with dilute sulfuric acid and segmenting it with carbon dioxide-free air, so that the carbon dioxide in the sample is expelled into the air segments. The air... 

Titration reaction (the acetic and hydrochloric acids are titrated with sodium hydroxide). 

Procedure Weigh accurately about 0.2 g of sodium metabisulphite and dissolve in 50.0 ml of 0.1 N iodine solution and add 1 ml hydrochloric acid. Titrate the excess of iodine with 0.1 N sodium thiosulphate employing freshly prepared starch solution, added towards the end of the titration, as indicator. Each ml of 0.1 N iodine is equivalent to 0.0047453 g of Na Oj. 

Nitrogen. — Dissolve 10 gm. of reduced iron in a mixture of 20 cc. of concentrated sulphuric acid (sp. gr. 1.84) and 200 cc. of water, with the aid of heat. Allow to cool, and when cold add 100 cc. of sodium hydroxide solution (sp. gr. 1.3), and distil off about 50 cc., collecting the distillate in a receiver containing about 20 cc. of water and 2 to 3 cc. of decinormal hydrochloric acid. Titrate the distillate with decinormal potassium hydroxide, using methyl orange as indicator. The ammonia should not have neutralized more than 0.2 cc. of the acid. 

Dissolve 0.10 to 0.15 gm. of dried potassium iodate in 20 cc. of water, add 3 gm. of potassium iodide and 5 cc. of hydrochloric acid. Dilute with 50 cc. of water, and titrate the liberated iodine with decinormal sodium thiosulphate. 

When ethylenediamme is. aided to a solution ofcobaltfll) chloride hexahydraic in concentrated hydrochloric acid, a Hue crystalline solid is obtained in 80% yield. Analysis of this compound shows ihal it contains 14.16% N. 12.13% C. 5.09% H. and 53.70% Cl. The effective magnetic moment is measured as 4.6 BM. The blue complex dissolves in water to give a pink solution, the conductivity of which is 852 ohm 1 cm mot"1 at 25 °C. The visible spectrum of a dmso solution of the complex his bands centered at 3217.5610. and 15,150 cm" (molar absorptivity = 590 mol-1 Lem-1), but for a water solution, the absorptions occur et 8000. —16.00031x119.400cm-I(nx)lar absorptivity = 5 mol-1 Lem-1). In u titration with sodium hydroxide, each mole of Ihe complex neutralizes four moles of base. Determine the formula and structure of the complex. Account for dll reactions and observations. 

Three methods for determining mineral carbon dioxide in coal were investigated using bituminous coal. The titrimetric method is claimed to be superior to either of the then-used British standard gravimetric or manometric methods (BS 1016). The procedure involves the decomposition of carbonate minerals with hydrochloric acid and absorption of the evolved carbon dioxide in a mixture of benzylamine, ethanol, and dioxan. This mixture forms a stable salt of benzylcar-bamic acid, which is then titrated with sodium methoxide. The method was said to be suitable for all concentrations of carbon dioxide. It is especially accurate for low concentrations, and it is much more rapid than other methods tested. 

Another official procedure (30) involves digestion of an accurately weighed sample of saccharin in hydrochloric acid. The resulting ammonium salt is reacted with sodium hydroxide and the liberated ammonia is distilled into 0.1 N sulphuric acid. The excess of the acid is determined by titrating with sodium hydroxide using methyl red solution as indicator. 

Silver sulfadiazine is dissolved in dilute hydrochloric acid and determined by titration with sodium nitrite solution (assay of the primary aromatic amine function). The endpoint detection is commonly biamperometric (27). 

Preparation of 9-methyl-3-[(2-methyl-l-H-imidazol-l-yl)methyl]-l,2,3,9-tetrahydro-4H-carbazol-4-one hydrochloride dihydrate The process above described is followed, except that after cooling down the reaction mixture to room temperature after boiling, 20 ml of 37% aqueous hydrochloric acid are added thereto. Then, the precipitate is filtered off, washed with isopropanol and dried to obtain 2.40 g (65.6%) of the title salt, m.p. 178°-180°C. The active agent content of the product was found to be 100.3% based on potentiometric titration with sodium hydroxide solution. The theoretical water content is 9.85% (calculated for C18H19N30HCl2H20).The water content measured is 10.03%. 

Calcium Carbonate. Ten g. of nitrocellulose, 100 c.c. of N hydrochloric acid and too c.c. water are put into a stoppered cylinder, shaken for an hour, and the excess of acid titrated with N o sodium carbonate, using methyl orange as indicator. 

The USP method (12) for the assay of sulfacetamide is based on nitrite titration followed by electrometric end-point determination using platinum electrodes. A 500 mg quantity of the drug is transferred to an open vessel. 20 ml of hydrochloric acid and 50 ml of water are added, the solution stirred until the content dissolved, cooled to about 15°, and slowly titrated with 0.1 M sodium nitrite. Each ml of 0.1 M sodium nitrite is equivalent to 21.42 mg of C8H10N2O3S. In the BP method (13), sulfacetamide sodium is assayed by amperometric titration. A 0.5 g quantity of the substance is dissolved in a mixture of 50 ml of water and 20 ml of 2 M hydrochloric acid and 3 g of potassium bromide are added. The solution is cooled in ice and sulfacetamide content determined amperometrically by titration with sodium nitrite. Each ml of 0.1 M sodium nitrite is equivalent to 0.02362 g of CsH9N2Na03S. 

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