Acidity equivalent weights

Carbon dioxide, 184, 358, 359 solid see Dry Ice Carbon disulphide, 767 purification of, 175 Carbon monoxide, 185, 1003, 1004 Carbon, decolourising, 127, 128 Carbon tetrachloride, 733, 815 drying of, 734 purification of, 176 Carbonyl chloride, 185 Carborundum chips, 4 Carboxylic acids, equivalent weights of, 1071 ... 

The second activation maximum for Echinocystis Factor I is approximately 30 mfi higher than that of gibberellic acid. The intensity of fluorescence is only about 3% that of gibberellic acid. Microspectrophotometric techniques for the determination of the acid equivalent weight (II) and of ethylenic double bonds (II) give a ratio of 0.75 double bond per acid equivalent in this fraction. 

Vacuum-still bottoms from the H-coal liquefaction process were separated into acid, neutral, and basic fractions by precipitation with acids or by extraction with bases. About one-third of the preasphaltene and one-sixth of the asphaltene fraction were precipitated by acids equivalent weights of the bases were in the range 1200-1800 for preasphaltenes and 600-800 for asphaltenes. The acidic components were obtained either by extraction with aqueous sodium hydroxide or by extraction with benzyltrimethylammonium hydroxide in methanol. About one-fifth of the asphaltene and one-fourth of the presasphaltene fractions were obtained as acids, and up to 10% as amphoteric substances. Nitrogen and sulfur were present in all fractions found. Deno axidation (CF3C02H, H202, H 04) gave dicarboxylic acids from malonic to adipic in addition to mono acids. 

Vinyl dispersion resins have typically consisted of inert homopolymer or copolymers of vinyl chloride and vinyl acetate, and although the inertness has been of importance for a multitude of applications, there are occasions when reactive functionality is an aid. An example of such a reactive vinyl resin is Geon 137, a carboxyl modified dispersion resin with a carboxyl content equivalent to 1.79% on a resin weight basis or an acid equivalent weight of about 2500. One adhesive application of considerable interest is in the production of flocked product, notably wall and floor coverings. A 50% replacement of standard copolymer dispersion resin with carboxyl functional resin doubles the force required to pluck fibers loose. Test results of laminating carboxylic vinyl plastisol with nylon fabric have shown a threefold increase in adhesion. Such plastisols also show improved adhesion to glass and polyester fabrics. ... 

The saponiflcatlon equivalent or the equivalent weight of an ester is that weight in grams of the ester from which one equivalent weight of acid is obtainable by hydrolysis, or that quantity which reacts with one equivalent of alkali. The saponification equivalent is determined in practice by treating a known weight of the ester with a known quantity of caustic alkali used in excess. The residual alkali is then readily determined by titration of the reaction mixture with a standard acid. The amount of alkafi that has reacted with the ester is thus obtained the equivalent can then be readily calculated. 

Equivalent weight of an acid. Determine the equivalent weight of the acid (use about 0 2 g.) by titration with standard ca. 0- N alkali... 

H0CH3)3CNHH3 121.137 Tris(hydroxymethyl)aminomethane is available commercially as a primary standard. Dry at 100-103°C (<110°C). In titrations with a strong acid the equivalence point is at about pH 4.5-5. Equivalent weight is the formula weight. [J. H. Eossum, P. C. Markunas, and J. A. Riddick, Anal. Chem., 23 491 (1951).]... 

Heat reagent-grade material for 1 hr at 255-265°C. Cool in an efficient desiccator. Titrate sample with acid to pH 4-5 (first green tint of bromocresol green), boil the solution to eliminate the carbon dioxide, cool, and again titrate to pH 4-5. Equivalent weight is one-half the formula weight. 

Eor phosphoric acid, the number of equivalents is the number of Fi ions donated to the base. Eor the reactions in (a), (b), and (c) the number of equivalents are 3, 2, and 1, respectively. Thus, the calculated equivalent weights and normalities are... 

Two useful characterization applications involving acid-base titrimetry are the determination of equivalent weight, and the determination of acid-base dissociation constants. 

Equivalent Weights Acid-base titrations can be used to characterize the chemical and physical properties of matter. One simple example is the determination of the equivalent weighf of acids and bases. In this method, an accurately weighed sample of a pure acid or base is titrated to a well-defined equivalence point using a mono-protic strong acid or strong base. If we assume that the titration involves the transfer of n protons, then the moles of titrant needed to reach the equivalence point is given as... 

A 0.2521-g sample of an unknown weak acid is titrated with a 0.1005 M solution of NaOH, requiring 42.68 mL to reach the phenolphthalein end point. Determine the compound s equivalent weight. Which of the following compounds is most likely to be the unknown weak acid ... 

A 250.0-mg sample of an organic weak acid was dissolved in an appropriate solvent and titrated with 0.0556 M NaOH, requiring 32.58 ml to reach the end point. Determine the compound s equivalent weight. 

An acid-base titration can be used to determine an analyte s equivalent weight, but cannot be used to determine its formula weight. Explain why. 

The lower equivalent weight of magnesium hydroxide compared to caustic soda, hydrated lime, and soda ash reduces the stoichiometric amounts necessary to neutralize a given amount of acid. Depending on relative alkah costs, magnesium hydroxide can offer the advantage of lower chemical costs. 

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

Apparent equivalent weight can be deterrnined by titration with hydrochloric acid using a bromocresol green indicator. Calculations give the equivalent weight of total amines and are not specific for the mono-, di- or tri alkan olamines. 

The tria2ine ring-containing product 1,3,5-triglycidyl isocyanurate (6) is synthesized by glycidylation of cyanuric acid with epichlorohydrin. The commercial product is a crystalline powder that exhibits an epoxy equivalent weight of ca 108 and softens in the 85—110°C range (see Cyanuric AND ISOCYANURIC acids). 

There were obtained 109 g 3-acetylaminomethyl-5-amino-2,4,6-triiodobenzoic acid which decomposes and melts at approximately 230°C. The equivalent weight was determined experimentally as being 591, as compared to a theoretical value of 586. 

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