Sodium hydroxide equivalent weight

An unknown acid was titrated with 23.1 mL of 0.1 A sodium hydroxide. The weight of the acid was 120.8 mg. What is the equivalent weight of the acid ... 

Alkalinity measurement is also required for the determination of active matter by difference and equivalent weight calculations. It can be determined as two of the following compounds sodium bicarbonate, sodium carbonate, or sodium hydroxide. The sample is titrated to a phenolphthalein endpoint to determine the sodium hydroxide/sodium carbonate content. An added measure of acid converts any bicarbonate to carbon dioxide, which is subsequently removed from the solution. Back-titration of the excess acid gives a measure of the amount of bicarbonate and/or carbonate present. 

If the dicarboxylic acid has been present in excess in the reaction mixture, then the resulting polyester uses up more sodium hydroxide for the same Molecular weight of the polyester which has been prepared by the complete equivalencies of the monomers. If the amount of dicarboxylic acid during the synthesis of the ester is very high and if all the molecules of the polymers contain carboxyl groups at both ends, then the consumption of sodium Organisation and Qualities... 

A weight of compound, containing about 0-05 g. of fluorine, was dissolved in 10 ml. of dry alcohol and metallic sodium (about 0 5 g., i.e. at least 5 equivalents) was added. After the sodium had dissolved, the mixture was gently heated under reflux for 5 min.,8 and then washed out with about 100 ml. of water into a beaker, made acid to bromophenol blue with dilute nitric acid and then just alkaline with 10 per cent sodium hydroxide solution. Three ml. of 10 per cent sodium chloride solution were added and the solution was diluted to 250 ml. One ml. of concentrated hydrochloric acid was added, and the solution heated on a water-bath to about 80°. Then 5-0 g. of finely powdered A.R. lead nitrate were added with stirring (still at 80°). As soon as all the lead nitrate had dissolved, 5-0 g. of crystalline sodium acetate were added, with vigorous stirring. The product was then heated on the water-bath for 15 min. and cooled in ice, and the precipitate was filtered off on a Swedish filter paper. It was washed once with water, four times with saturated PbClF solution... 

From the above equation it is evident that two moles of sodium hydroxide is needed to neutralize one mole of tartaric acid, therefore, the equivalent weight of tartaric acid is 75.04 g. Hence, each millilitre of 1 N sodium hydroxide is equivalent to 0.07504 g (i.e., 1 meq) of tartaric acid. 

Busulphan is first hydrolyzed by refluxing it with water and two moles methanesulphonic acid (from one mole of Busulphan) thus generated, titrated with 0.1 N sodium hydroxide employing phenolphthalein as indicator. Hence, the equivalent weight of busulphan is 123.145 g. Therefore, each millilitre of 0.1 N sodium hydroxide is equivalent to 0.01232 g of busulphan. 

Procedure Weigh 20 tablets and crush them in a pestle mortar and find out the average weight of a single tablet. Accurately weigh 0.5 g equivalent of papaverine hydrochloride and dissolve in 15 ml of DW. Add to it 15 ml of 2 M sodium hydroxide and extract with 50 ml of chloroform and then with successive 25 ml quantities of chloroform until complete extraction is affected. Wash the combined extracts with two 5 ml quantities of DW and wash the combined aqueous extract with two 10 ml quantities of chloroform. Add the chloroform to the main chloroform extract, evaporate to a small volume, add 2 ml of absolute ethanol, evaporate to dryness and dry the residue to constant weight at 105°C. 

The neutralization equivalent is a useful means of determining the molecular weight of a carboxylic acid. The process begins with a simple neutralization reaction of acid with standard base (usually sodium hydroxide). The reaction is... 

The reaction actually involves the sodium salt of bisphenol A since polymerization is carried out in the presence of an equivalent of sodium hydroxide. Reaction temperatures are in the range 50-95°C. Side reactions (hydrolysis of epichlorohydrin, reaction of epichlorohydrin with hydroxyl groups of polymer or impurities) as well as the stoichiometric ratio need to be controlled to produce a prepolymer with two epoxide end groups. Either liquid or solid prepolymers are produced by control of molecular weight typical values of n are less than 1 for liquid prepolymers and in the range 2-30 for solid prepolymers. 

The only practical difference between potassium and sodium hydroxide, as far as photography is concerned, is that 10 parts by weight of sodium are the equivalent of 14 parts by weight of potassium. Also, potassium hydroxide is more soluble, meaning more will go into solution than sodium hydroxide. The limit of sodium hydroxide in water is 50% the limit for potassium hydroxide is somewhat higher. 

Shao et al. recommended the use of a simultaneous fluorimetric method for the determination of the dissolution rate of dipyridamole and aspirin tablets [34]. The powdered tablets (equivalent to weight of one tablet) of dipyridamole and aspirin were dissolved in simulated digestive fluids at 37°C, cooled, and diluted to 1 L with simulated digestive juice. The solution was filtered, and a 1 mL portion of the filtrate was mixed with 0.1 M sodium hydroxide and then set aside at room temperature for 1 h. The solution was mixed with 8 mL of phosphoric acid buffer (pH 6.8) and fluorimetrically detected for dipyridamole at 493 nm (excitation at 418 nm). The coefficients of variation for within-day and within 5 days were 2% for both dipyridamole and aspirin. 

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