Sodium carbonate primary standard

In a standardization experiment, 0.4920 g of primary standard sodium carbonate (Na2C03) was exactly neutralized by 19.04 mL of hydrochloric acid solution. What is the molarity of the HC1 solution Refer to Equation (4.7) for the reaction involved. 

Primary standard sodium carbonate may also be used to standardize acid solutions. Sodium carbonate also possesses all the qualities of a good primary standard, like KHP and THAM. When titrating sodium carbonate, carbonic acid, H2C03, is one of the products and must be decomposed with heat to push the equilibria below to completion to the right ... 

Sodium carbonate [497-19-8] M 106.0. Crystd from water as the decahydrate which was redissolved in water to give a near-saturated soln. By bubbling CO2, NaHCO3 was ppted. It was filtered, washed and ignited for 2h at 280° [MacLaren and Swinehart JACS 73 1822 7957]. Before being used as a volumetric standard, analytical grade material should be dried by heating at 260-270° for 0.5h and allowed to cool in a desiccator. For prepcU ation of primary standard sodium carbonate, see PAC 25 459 1969. 

Sulfuric Acid, 1 N (49.04 g H2S04 per 1000 mL) Add slowly, with stirring, 30 mL of sulfuric acid to about 1020 mL of water, allow to cool to 25°, and standardize by titration against primary standard sodium carbonate (Na2C03) as directed under 1 N Hydrochloric Acid. Each 52.99 mg of Na2C03 is equivalent to 1 mL of 1 N Sulfuric Acid. 

Na2C03 NaHCOj 2H2O. These minerals find wide use in the glass industry as well as many others. Primary-standard sodium carbonate is manufactured by extensive purification of these minerals. 

The molarity of a perchloric acid solution was established by titration against primary-standard sodium carbonate (product CO2) the following data were obtained. I... 

Principle The soda ash is dissolved in water and titrated to a bromcresol green end point with standard hydrochloric acid. The. hydrochloric acid is standardized against primary standard sodium carbonate. Weigh sodium carbonate and soda ash unknown by difference. 

You prepared a solution of hydrochloric acid and standardized it by titration of primary standard sodium carbonate. The temperature during the standardization was 23°C, and the concentration was determined to be 0.11272 M. The heating system in the laboratory malfunctioned when you used the acid to titrate an unknown, and the temperature of the solution was 18°C. What was the concentration of the titrant ... 

An approximate 0.1 M hydrochloric acid solution is prepared by 120-fold dilution of concentrated hydrochloric acid. It is standardized by titrating 0.1876 g of dried primary standard sodium carbonate ... 

A hydrochloric acid solution is standardized by titrating 0.2329 g of primary standard sodium carbonate to a methyl red end point by boihng the carbonate solution near the end point to remove carbon dioxide. If 42.87 mL acid is required for the titration, what is its molarity ... 

Thermogravimetry is a valuable technique for the assessment of the purity of materials. Analytical reagents, especially those used in titrimetric analysis as primary standards, e.g. sodium carbonate, sodium tetraborate, and potassium hydrogenphthalate, have been examined. Many primary standards absorb appreciable amounts of water when exposed to moist atmospheres. TG data can show the extent of this absorption and hence the most suitable drying temperature for a given reagent may be determined. 

Typically, acid soils are titrated with a sodium or calcium hydroxide [NaOH or Ca(OH)2] solution and basic soils with hydrochloric acid (HC1), and pH changes are most commonly followed using a pH meter. Carbonates in basic soils release C02 during treatment with HC1, thus making the titration more difficult. For this reason, carbonates are often determined by other methods. It is important to keep in mind that basic solutions react with carbon dioxide in air and form insoluble carbonates. This means that either the basic titrant is standardized each day before use or the solution is protected from exposure to carbon dioxide in air. Specific descriptions of titrant preparation, primary standards, and the use of indicators and pH meters in titrations can be found in Harris [1] and in Skoog et al. [2],... 

Examples of primary standards include sodium carbonate (NajCOj), oxalic acid (H2C20. 2H20) and potassium hydrogenphthalate. 

Sodium hydroxide is not a primary standard - it has a relatively low GFM and readily absorbs moisture, making it unstable as a solid. The solution also absorbs carbon dioxide and so its concentration is not constant. The accurate concentration of a solution of sodium hydroxide can be determined by titrating it with a solution of a primary standard such as potassium hydrogenphthalate. 

Primary standard grade Na2C03 is commercially available. Alternatively, recrystallized NaHC03 can be heated for 1 h at 260°-270cC to produce pure Na2C03. Sodium carbonate is titrated with acid to an end point of pH 4-5. 

Sodium Hydroxide, 1N (40.00 g NaOH per 1000 mL) Dissolve about 40 g of sodium hydroxide (NaOH) in about 1000 mL of carbon dioxide-free water. Shake the mixture thoroughly, and allow it to stand overnight in a stoppered bottle. Standardize the clear liquid as follows Transfer about 5 g of primary standard potassium biphthalate [ KHCgH4(COO )2], previously dried at 105° for 2 h and accurately weighed, to a flask, and dissolve it in 75 mL of carbon dioxide-free water. If the potassium biphthalate is in the form of large crystals, cmsh it before drying. To the flask add 2 drops of Phenolphthalein TS, and titrate with the sodium hydroxide solution to a permanent pink color. Calculate the normality. Each 204.2 mg of potassium biphthalate is equivalent to 1 mL of 1 N Sodium Hydroxide. 

Sodium Thiosulfate, 0.1 N (15.81 g Na2S203 per 1000 mL) Dissolve about 26 g of sodium thiosulfate (Na2S203-5H20) and 200 mg of sodium carbonate (Na2C03) in 1000 mL of recently boiled and cooled water. Standardize the solution as follows Weigh accurately about 210 mg of primary standard potassium dichromate, previously pulverized and dried at 120° for 4 h, and dissolve in 100 mL of water in a 500-mL glass-stoppered flask. Swirl to dissolve the sample, remove the stopper, and quickly add 2 g of sodium bicarbonate, 3 g of potassium iodide, and 5 mL of hydrochloric acid. Stopper the flask, swirl to mix, and let stand in the dark for 10 min. Rinse the stopper and inner walls of the flask with water, and titrate the liberated iodine with the sodium thiosulfate solution until... 

When a solution of standard base is used only for titration of strong acids, a small amount of carbonate is not a serious source of error provided the end point is taken with an indicator that changes color at a pH of about 4 or 5. For standardizing such carbonate-containing solutions, potassium hydrogen phthalate is an unsuitable primary standard. An alternative is pure potassium chloride, which is passed through a cation-exchange column, converted to hydrochloric acid, and titrated with the sodium hydroxide. 

Acids are frequently standardized against weighed quantities of sodium carbonate. Primary-standard grade sodium carbonate is available commercially or can be prepared by heating purified sodium hydrogen carbonate to 270°C to 300°C for 1 hour ... 

Let us now describe the use of a few primary standards for acids and bases. One primary standard for solutions of acids is sodium carbonate, Na2C03, a solid compound. 

Sodium carbonate is often used as a primary standard for acids. 

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