Hydrochloric acid titration with sodium hydroxide

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. 

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. 

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. 

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). 

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. 

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. 

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%. 

Neutralization reactions can also be looked at through conductivity tests. If a conductivity titration is performed with diluted hydrochloric acid and diluted sodium hydroxide solution (see E7.14), one would attain a certain minimum of electrical conductivity at the equivalence point, but it is not zero (see left diagram of Fig. 7.15) Na + (aq) ions and CF(aq) ions are left behind in the solution and are responsible for the minimal conductivity. The decrease in conductivity is often explained by the misconception that the absolute number of ions decreases and that by the usual ionic equation from an initial number of four ions, only two remain ... 

Sodium cyanate, a reagent with a short shelf life, requiring frequent titration, has been used in cold, dilute acetic acid to convert o-aminoamides to 2-ureidobenzamides (155), which can be cyclized to quinazoline-2,4-diones (see 1) by heating at 100°C with 7 N hydrochloric acid, 8 N sodium hydroxide,257 or simply in water.258 No yields were published. Ammonium thiocyanate, similarly acidified, was used to convert 2-aminothiophene-3-carboxamide to 2-thioxothieno[2,3-d]pyrimidin-4-ones (see 12).255... 

Experiment 14.4 Azeotropic behavior of hydrochloric acid. When diluted hydrochloric acid in a porcelain bowl is heated, it is primarily the water that evaporates until the residue reaches the azeotropic composition. Further separation is not possible any longer at this point, because only hydrochloric acid with 20 % HCl is distilled off. However, when concentrated hydrochloric acid is heated, it is mostly hydrogen chloride that evaporates until, again, the azeotropic point is reached. The residues in both cases exhibit identical concentrations of hydrochloric acid. This can be easily demonstrated by titration with sodium hydroxide solution. 

At room temperature, the pH of a sodium borate solution is 9.3. The buffering capacity of boric acid-borate solutions was evaluated at 350°C and 3500 psia by measuring the pH change during titrations with sodium hydroxide and hydrochloric acid[13]. The borate buffer titration experiments were conducted at 350°C and 24.1 MPa (3500 psia) where the water density is 0.622 g/mL and the pKa of boric acid is approximately 9.6. The concentration of sodium borate in the feed solutions was fixed at 6.25 X 10 m, which corresponded to a total boron concentration of 0.025 m. At 350°C, the measurable pH ranges of the various optical indicators are 9.0-11.0 for 2-naphthol, 7.0-9.0 for 2-naphthoic acid, 3.0-5.0 for collidine, and 2.0-4.0 for acridine. The indicator 2-naphthol was used to measure pH for the titration of the borate buffer with NaOH which began at pH of 9.5 and ended at 10.5. For the titration with HCl, 2-naphthol, 2-naphthoic acid, and collidine were used in series to measure pH values between 9.5 and 3.0. 

Figure 4.23 shows a flask containing hydrochloric acid with an unknown amount of HCl being titrated with sodium hydroxide solution, NaOH, of known molarity. The reaction is... 

Reference to Tables 2.2 and 2.3 on p. lb and n will confirm that there is no difference in the lesults obtained (in 0 01 molai solutions) for benzoic acid when titrated with sodium hydroxide or for sodium benzoate when titrated with hydrochloric acid. The latter method, which is essentially the titiation of an anion, is advantageous for spaiingl) stduble acids which ma> decompose when heated to effect dissolution these should be dissolved in exacth 1 mole equivalent of cold sodium hydroxide so that the... 

Commercial Hquid sodium alumiaates are normally analyzed for total alumiaa and for sodium oxide by titration with ethylene diaminetetraacetic acid [60-00-4] (EDTA) or hydrochloric acid. Further analysis iacludes the determiaation of soluble alumiaa, soluble siHca, total iasoluble material, sodium oxide content, and carbon dioxide. Aluminum and sodium can also be determiaed by emission spectroscopy. The total iasoluble material is determiaed by weighing the ignited residue after extraction of the soluble material with sodium hydroxide. The sodium oxide content is determiaed ia a flame photometer by comparison to proper standards. Carbon dioxide is usually determiaed by the amount evolved, as ia the Underwood method. 

The EGTA solution may be standardised by titration of a standard (0.05M) calcium solution, prepared by dissolving 5.00 g calcium carbonate in dilute hydrochloric acid contained in a 1 L graduated flask, and then after neutralising with sodium hydroxide solution diluting to the mark with de-ionised water, use zincon indicator in the presence of Zn-EGTA solution (see below). 

Notes. (1) Somewhat sharper end points may be obtained if the sample of water is first acidified with dilute hydrochloric acid, boiled for about a minute to drive off carbon dioxide, cooled, neutralised with sodium hydroxide solution, buffer and indicator solution added, and then titrated with EDTA as above. 

In many titrations, one solution—either the analyte or the titrant—contains a weak acid or base and the other solution contains a strong base or acid. For example, if we want to know the concentration of formic acid, the weak acid found in ant venom (1), we can titrate it with sodium hydroxide, a strong base. Alternatively, to find the concentration of ammonia, a weak base, in a soil sample, titrate it with hydrochloric acid, a strong acid. Weak acids are not normally titrated with weak bases, because the stoichiometric point is too difficult to locate. 

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. 

On p. 124 you saw that it was possible to prepare a soluble salt by reacting an acid with a soluble base (alkali). The method used was that of titration. Titration can also be used to find the concentration of the alkali used. In the laboratory, the titration of hydrochloric acid with sodium hydroxide is carried out in the following way. 

The titration of an acid solution with a standard solution of alkali will determine the amount of alkali which is equivalent to the amount of acid present (or vice versa). The point at which this occurs is called the equivalence point or end-point. For example, the titration of hydrochloric acid with sodium hydroxide can be expressed as follows ... 

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