Hydrochloric acid, determination

The pH of a 50.00-mL sample of 0.06000 M strontium hydroxide is measured as it is titrated with a 0.1200 M hydrochloric acid. Determine the pH of the solution after the following total volumes of hydrochloric acid have been added. 

Dissolve 0.3 g of omeprazole sodium in 50 ml of water R. Titrate with 0.1 M hydrochloric acid, determining the end point potentiometrically as directed in the general procedure (2.2.20). One milliliter of 0.1 M hydrochloric acid corresponds to 36.74 of Ci7H18N3Na03S. 

Procedure Transfer about 2 g of sample, accurately weighed, into a 250-mL beaker, and dissolve it in 100 mL of acetone. Add 25 mL of 1 N Di-n-butylamine by pipet, allow the mixture to stand for 5 min, and titrate with 1 N hydrochloric acid, determining the endpoint potentiomet-rically. Perform a blank titration (see General Provisions), and make any necessary correction. Calculate the percent Dimethyl Dicarbonate in the sample taken by the formula... 

Titrate the sample and the blank to pH 3.60 with 0.5 N hydrochloric acid, determining the endpoint potentiomet-rically. Calculate the percentage, by weight, of C5H802 in the sample by the formula... 

THE CHEMICAL ACTIVITY OF THE IONS OF HYDROCHLORIC ACID DETERMINED BY ELECTROMOTIVE FORCE MEASUREMENTS... 

Extraction of Ca with Azo-azoxy BN. Add sufficient 5M NaOH to the sample solution to make the NaOH concentration 0.5-1 M. Shake the solution for 1 min with the solution of Azo-azoxy BN. Strip calcium from the extract with a small volume of 1M hydrochloric acid. Determination of Ca. The sample solution should contain not more than 30 pg of Ca, and be free from ammonium salts and Analytical Group I-III metals (to mask small amounts of these metals, add 10 mg each of KCN and Na2S. Neutralize the sample solution (to pH 7-8) with NaOH or HCl, and add 20 mg of Na2S04. Add 12 ml of the GBHA solution and 1 ml of 1 M NaOH, and dilute the solution with water to the mark in a 25-ml standard flask. After 10 min, measure the absorbance of the solution at 516 nm against a blank solution. 

Drop 1 g. of sodium into 10 ml. of ethyl alcohol in a small flask provided with a small water condenser heat the mixture until all the sodium has dissolved. Cool, and add 1 g. of the ester and 0-5 ml. of water. Frequently the sodium salt of the acid will be deposited either at once or after boiling for a few minutes. If this occurs, filter oflF the solid at once, wash it with a little absolute ethyl alcohol (or absolute methylated spirit), and convert it into the p-bromophenacyl ester, p-nitro-benzyl ester or S-benzyl-tso-thiuronium salt (for experimental details, see Section 111,85). If no solid separates, continue the boiling for 30-60 minutes, boil oflF the alcohol, allow to cool, render the product just neutral to phenolphthalein with dilute sulphuric or hydrochloric acid, convert the sodium salt present in solution into a crystalline derivative (Section 111,85), and determine its melting point. 

Dissolve 10 g. of lactose (1) in 100 ml. of nitric acid, sp. gr. 115, in an evaporating dish and evaporate in a fume cupboard until the volume has been reduced to about 20 ml. The mixture becomes thick and pasty owing to the separation of mucic acid. When cold, dilute with 30 ml. of water, filter at the pump and set the filtrate A) aside. Wash the crude acid with cold water. Purify the mucic acid by dissolving it in the minimum volume of dilute sodium hydroxide solution and reprecipitating with dilute hydrochloric acid do not allow the temperature to rise above 25°. Dry the purified acid (about 5 g.) and determine the m.p. Mucic acid melts with decomposition at 212-213°. 

Method 1. Treat 2 0 g. of the mixture of amines with 40 ml. of 10 per cent, sodium hydroxide solution and add 4 g. (3 ml.) of benzenesulphonyl chloi de (or 4 g. of p-toluenesulphonyl chloride) in small portions. Warm on a water bath to complete the reaction. Acidify the alkaline solution with dilute hydrochloric acid when the sulphonamides of the primary and secondary amines are precipitated. Filter off the solid and wash it with a little cold water the tertiary amine will be present in the filtrate. To convert any disulphOnamide that may have been formed from the primary amine into the sulphonamide, boil the solid under reflux with 2 0 g. of sodium dissolved in 40 ml. of absolute ethyl alcohol for 30 minutes. Dilute with a little water and distil off the alcohol filter off the precipitate of the sulphonamide of the secondary amine. Acidify the filtrate with dilute hydrochloric acid to precipitate the derivative of the primary amine. Recrystallise the respective derivatives from alcohol or from dilute alcohol, and identify them inter alia by a determination of the m.p. 

This may be determined roughly by treating a small test portion with 3-4 ml. of hot water and acidifying with concentrated hydrochloric acid the absence of a precipitate in the warm solution indicates the essential completeness of the reaction. Salicylic acid is sparingly soluble and p-hydroxybenzoic acid is relatively soluble under these conditions. 

The hydrolysis by alkali is illustrated by the following experimental details for benzamido. Place 3 g. of benzamide and 50 ml. of 10 per cent, sodium hydroxide solution in a 150 ml. conical or round-bottomed flask equipped with a reflux condenser. Boil the mixture gently for 30 minutes ammonia is freely evolved. Detach the condenser and continue the boiling in the open flask for 3-4 minutes to expel the residual ammonia. Cool the solution in ice, and add concentrated hydrochloric acid until the mixture is strongly acidic benzoic acid separates immediately. Leave the mixture in ice until cold, filter at the pump, wash with a little cold water and drain well. RecrystaUise the benzoic acid from hot water. Determine the m.p., and confirm its identity by a mixed m.p. test. 

If an appreciable amount of residue remains, note its colour. Add a few drops of water and test the solution (or suspension) with htmus or with Universal indicator paper. Then add a httle dilute hydrochloric acid and observe whether efiervesceiice occurs and the residue dissolves. Apply a flame test with a platinum wire on the hydrochloric acid solution to determine the metal present. (In rare cases, it may be necessary to subject a solution of the residue to the methods of qualitative inorganic analysis to identify the metal or metals present.) If the flame test indicates sodium, repeat the ignition of the substance on platinum foil. 

Sensory perception is both quaUtative and quantitative. The taste of sucrose and the smell of linalool are two different kinds of sensory perceptions and each of these sensations can have different intensities. Sweet, bitter, salty, fmity, floral, etc, are different flavor quaUties produced by different chemical compounds the intensity of a particular sensory quaUty is deterrnined by the amount of the stimulus present. The saltiness of a sodium chloride solution becomes more intense if more of the salt is added, but its quaUty does not change. However, if hydrochloric acid is substituted for sodium chloride, the flavor quahty is sour not salty. For this reason, quaUty is substitutive, and quantity, intensity, or magnitude is additive (13). The sensory properties of food are generally compHcated, consisting of many different flavor quaUties at different intensities. The first task of sensory analysis is to identify the component quahties and then to determine their various intensities. 

Only acids are sour. Sourness is not identical to chemical acidity or pH, which is a function of the hydrogen ion concentration, but also appears to be a function of the entire acid molecule. A combination of pH and acid concentration determines the actual degree of the sour taste. At the same pH, any organic acid, eg, citric acid, exhibits a far greater sourness than a mineral acid, eg, hydrochloric acid (27,28). 

Analyses of alloys or ores for hafnium by plasma emission atomic absorption spectroscopy, optical emission spectroscopy (qv), mass spectrometry (qv), x-ray spectroscopy (see X-ray technology), and neutron activation are possible without prior separation of hafnium (19). Alternatively, the combined hafnium and zirconium content can be separated from the sample by fusing the sample with sodium hydroxide, separating silica if present, and precipitating with mandelic acid from a dilute hydrochloric acid solution (20). The precipitate is ignited to oxide which is analy2ed by x-ray or emission spectroscopy to determine the relative proportion of each oxide. 

Iodine monochloride [7790-99-0] ICl, mol wt 162.38, 78.16% I, is a black crystalline soHd or a reddish brown Hquid. SoHd ICl exists ia two crystalline modifications the a-form, as stable mby-red needles, d = 3.86 g/mL and mp 27.3°C and as metastable brownish red platelets, d = 3.66 g/mL, mp 13.9°C and bp 100°C (dec). Iodine monochloride is used as a halogenation catalyst and as an analytical reagent (Wij s solution) to determine iodine values of fats and oils (see Fats and fatty oils). ICl is prepared by direct reaction of iodine and Hquid chlorine. Aqueous solutions ate obtained by treating a suspension of iodine ia moderately strong hydrochloric acid with chlorine gas or iodic acid (118,119). 

Titrations with dibutylamine [111-92-2] can also be used to determine the NCO content of isocyanates and prepolymers. Generally, an excess of amine in a suitable solvent such as chlorobenzene [108-90-7] is added to the sample. The resulting solution is allowed to react and the unreacted amine is back- titrated with dilute hydrochloric acid. For low NCO content levels, a colorimetric method is often used. The isocyanate-containing species is titrated with amine and the unreacted amine is deterrnined using malachite green [569-64-2]. 

Apparent equivalent weight deterrnined by titration with hydrochloric acid. APHA color determined by ASTM D1209, platinum—cobalt method. 

Analytical methods iaclude thin-layer chromatography (69), gas chromatography (70), and specific methods for determining amine oxides ia detergeats (71) and foods (72). Nuclear magnetic resonance (73—75) and mass spectrometry (76) have also been used. A frequentiy used procedure for iadustrial amine oxides (77) iavolves titratioa with hydrochloric acid before and after conversion of the amine to the quaternary ammonium salt by reaction with methyl iodide. A simple, rapid quaHty control procedure has been developed for the deterrniaation of amine oxide and unreacted tertiary amine (78). 

The sodium hydroxide is titrated with HCl. In a thermometric titration (92), the sibcate solution is treated first with hydrochloric acid to measure Na20 and then with hydrofluoric acid to determine precipitated Si02. Lower sibca concentrations are measured with the sibcomolybdate colorimetric method or instmmental techniques. X-ray fluorescence, atomic absorption and plasma emission spectroscopies, ion-selective electrodes, and ion chromatography are utilized to detect principal components as weU as trace cationic and anionic impurities. Eourier transform infrared, ft-nmr, laser Raman, and x-ray... 

A double end point, acid—base titration can be used to determine both sodium hydrosulfide and sodium sulfide content. Standardized hydrochloric acid is the titrant thymolphthalein and bromophenol blue are the indicators. Other bases having ionization constants in the ranges of the indicators used interfere with the analysis. Sodium thiosulfate and sodium thiocarbonate interfere quantitatively with the accuracy of the results. Detailed procedures to analyze sodium sulfide, sodium hydro sulfide, and sodium tetrasulfide are available (1). 

Analytical and Laboratory Operations. Sulfamic acid has been recommended as a reference standard in acidimetry (55). It can be purified by recrystaUization to give a stable product that is 99.95 wt % pure. The reaction with nitrite as used in the sulfamic acid analytical method has also been adapted for determination of nitrites with the acid as the reagent. This reaction is used commercially in other systems for removal of nitrous acid impurities, eg, in sulfuric and hydrochloric acid purification operations. 

A widely used procedure for determining trace amounts of tellurium involves separating tellurium in (1 1) hydrochloric acid solution by reduction to elemental tellurium using arsenic as a carrier and hypophosphorous acid as reductant. The arsenic, reduced from an addition of arsenite to the solution, acts as a carrier for the tellurium. The precipitated tellurium, together with the carrier, is collected by filtration and the filter examined directly in the wavelength-dispersive x-ray fluorescence spectrometer. 

In the determination of free formaldehyde in solution, eg, commercial reagents and pad bath formulation, the conditions of analysis allow hydrolysis of the /V-methy1o1 groups, usually between <1% and several percent. The NaOH formed is titrated with hydrochloric acid (82). Because of an incomplete reaction of sulfite with free formaldehyde, these low temperature methods (83) detect only 80—90% of the free formaldehyde present. Skill is important for correct results. 

The determination of tin in metals containing over 75 wt % tin (eg, ingot tin) requites a special procedure (17). A 5-g sample is dissolved in hydrochloric acid, reduced with nickel, and cooled in CO2. A calculated weight of pure potassium iodate (dried at 100°C) and an excess of potassium iodide (1 3) are dissolved in water and added to the reduced solution to oxidize 96—98 wt % of the stannous chloride present. The reaction is completed by titration with 0.1 Af KIO —KI solution to a blue color using starch as the indicator. 

The following discussion on health and safety aspects of titanium compounds is concerned only with the behavior of the titanium present in inorganic compounds and not with the effects of the compounds themselves. For example, titanium tetrachloride must be treated with care because of the effects of the hydrochloric acid and heat produced when it reacts with water, not because of the possible toxicity of titanium. Apart from very few exceptions, the inorganic compounds of titanium are generally regarded as having low toxicity. Because of the ubiquitous nature of the element and its compounds, average concentrations of titanium in blood have been determined at 130—160 Fg/L (182—184), with a typical value of 10 Fg/L in urine (185). 

Ash is a measure of residual sodium acetate. A simple method consists of dissolving the PVA in water, diluting to a known concentration of about 0.5 wt %, and measuring the electrical conductivity of the solution at 30°C. The amount of sodium acetate is estabUshed by comparing the result to a cahbration curve. A more lengthy method involves the extraction of the PVA with methanol using a Soxhlet extractor. The methanol is evaporated and water is added. The solution is titrated using hydrochloric acid in order to determine the amount of sodium acetate. 

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