Sodium hydrogen carbonate, titration

The percentage of sodium hydrogen carbonate, NaHC03, in a powder for stomach upsets is found by titrating with 0.275 M hydrochloric acid. If 15.5 mL of hydrochloric acid is required to react with 0.500 g of the sample, what is the percentage of sodium hydrogen carbonate in the sample ... 

Arsenic may be determined iodometricaQy. A dried sample of 150-200 mg. is mixed with 7 ml. of 15 N nitric acid and the solution boiled gently for 5-10 minutes. Three milliliters of 2 AT sodium bromate is then added and the mixture evaporated gently to dryness. The residue is taken up in 150 ml. of 4 M hydrochloric acid in an iodine flask then 1 g. of sodium hydrogen carbonate is cautiously mixed in to displace the air, followed by 1 g. of potassium iodide. The flask is then stoppered and allowed to stand 5 minutes. The contents are rapidly titrated with 0.05 N sodium thiosulfate to the disappearance of the iodine color. 

For the estimation of dissolved gases in water the former are generally first removed by boiling the water or by generating carbon dioxide m it m the latter case the bubbles of this gas carry out any dissolved gas, from winch the carbon dioxide is easily removed subsequently. Carbon dioxide itself may be conveniently estimated by titrating a measured volume of the water with sodium carbonate solution until phenolphthalem becomes coloured, the method depending on the neutrality of sodium hydrogen carbonate towards phenolphthalein.2... 

Potentiometric titration and colorimetric methods have been described for the determination of )5-chlorovinyldichloroarsine (Lewisite) . In the latter the organic arsenic is mineralized by refluxing with aqueous sodium hydrogen carbonate and then oxidized to... 

The Mohr titration must be carried out at a pH of 7 to 10 because chromate ion is the conjugate base of the weak chromic acid. Consequently, in more acidic solutions, the chromate ion concentration is too low to produce the precipitate near the equivalence point. Normally, a suitable pH is achieved by saturating the analyte solution with sodium hydrogen carbonate. 

Figure 15-5 illustrates that two end points are observed in the titration of sodium carbonate, the second being appreciably sharper than the first. It is apparent that the individual components in mixtures of sodium carbonate and sodium hydrogen carbonate can be determined by neutralization methods. 

The qualitative and quantitative determination of the constituents in a solution containing sodium carbonate, sodium hydrogen carbonate, and sodium hydroxide, either alone or admixed, provides interesting examples of how neutralization titrations can be employed to analyze mixtures. No more than two of these three constituents can exist in appreciable amount in any solution because reaction elim-... 

A voluminous literature exists on the acidic surface groups and their characterization. Therefore, this aspect of carbon surface chemistry can be here treated relatively briefly. The acidity of these groups opens a convenient way for their determination by titration with aqueous or alcoholic bases. The total of the Bronsted acids, including phenols, reacts with aqueous sodium hydroxide solutions by neutralization adsorption, while carboxylic acids are neutraflzed already by the weak base sodium hydrogen carbonate carboxylic anhydrides (lactones). Lactones and lactols are opened to the carboxylate form by the stronger base... 

An antacid tablet that contains sodium hydrogen carbonate is titrated with 0.200M HCl. If 0.400 g of the tablet requires 22.0 mL of HCl to reach the endpoint, what is the mass percent of NaHC03 in the tablet ... 

In the example given by Blaser and Worms, each 2 ml. of the resulting solution consumed the following amounts of iodine when titrated in a solution of sodium hydrogen carbonate ( ) 36.5 ml. of O.IW iodine ... 

Direct titration of CO2 with sodium hydroxide solution and conversion to sodium hydrogen carbonate has proved suitable as a determining process on site. The end-point of titration is at pH 8.3 and can either be determined electrometrically with the aid of a glass electrode and a pH meter or visually by using phenolphthalein. The process is suitable for direct... 

Certain lactones can be titrated with alkali although they are insoluble in sodium hydrogen carbonate. ot-Dibenzoylsuccinic lactone may be easily titrated, in... 

Figure 5.11 represents the titration curve of sodium carbonate titrated with a strong acid. Notice that there are two inflection points. This is because sodium carbonate is a dibasic base—there are two hydrogen ions accepted by the carbonate. On the way to the first inflection point, hydrogen ions are accepted by the carbonate to form bicarbonate ... 

Titration of carbonate ion with a strong acid. A solution of sodium carbonate may be titrated to the hydrogencarbonate stage (i.e. with one mole of hydrogen ions), when the net reaction is ... 

The pH at the equivalence point is thus approximately 3.7 the secondary ionisation and the loss of carbonic acid, due to any escape of carbon dioxide, have been neglected. Suitable indicators are therefore methyl yellow, methyl orange, Congo red, and bromophenol blue. The experimental titration curve, determined with the hydrogen electrode, for 100 mL of 0.1 M sodium carbonate and 0.1M hydrochloric acid is shown in Fig. 10.7. 

Better results are obtained by transferring 25.0 mL of the diluted hydrogen peroxide solution to a conical flask, and adding 100 mL 1M(1 20) sulphuric acid. Pass a slow stream of carbon dioxide or nitrogen through the flask, add 10 mL of 10 per cent potassium iodide solution, followed by three drops of 3 per cent ammonium molybdate solution. Titrate the liberated iodine immediately with standard 0.1M sodium thiosulphate in the usual way. 

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