Bases equivalent weights

The acid-base equivalent is defined as the weight (in grams) ef a substance that will provide, react with, or be equivalent to 1 mole of H+. us 1 mo e (98.1 g/mole) of H2S04 contains 2 moles ofH+ and its acid"base equivalent weight is... 

Neutralization reaction Equivalent of an acid Equivalent of a base Equivalent weight Colligative property... 

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... 

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. 

Hydroxyl Number. The molecular weight of polyether polyols for urethanes is usually expressed as its hydroxyl number or percent hydroxyl. When KOH (56,100 meg/mol) is the base, the hydroxyl number is defined as 56,100/equivalent weight (eq wt). Writing the equation as eq wt = 56,100/OH No. allows one to calculate the equivalents of polyol used in a urethane formulation, and then the amount of isocyanate required. The molecular weight can be calculated from these equations if the fiinctionahty, is known mol wt = / eq wt. 

Evidently, the titratable functions of M are two very strong bases, since the equivalent weight of M calculated from the curve was 391, corresponding to approximately half the molecular weight (791) calculated from the analyses discussed above. Apparently, one of the functions was due to the guanidino group of the isolated... 

In many of the largest boiler plants around the world AYT programs are often employed that commonly provide for hydrazine (as an oxygen scavenger) and a volatile amine such as morpholine (to boost the pH level). Where funds are limited, however, some facilities instead use ammonia as a pH booster because it is a low-cost item with a low equivalent weight and a high DR. Unfortunately, this approach may lead to downstream problems as ammonia becomes less chemically bound with increases in FW pH and a weaker base as temperatures rise. Consequently, a point is reached when ammonia ceases to further influence the pH level upward. 

Magnesium-based additives are commonly employed to treat boiler furnace area fouling and corrosion conditions. They are injected into heavy fuel oil or other combustible material. Cerium is superior in action to magnesium salts, however, because an equivalent weight of cerium increases the melting point of the deposit more than that of magnesium. 

A sample of 4.00 g of a solid acid was treated with 50.00 mL of 2.000 V NaOH, which dissolved it completely (by reacting with it). There was enough excess NaOH to require 10.07 mL of 1.000 N HC1 to neutralize the excess base. What is the equivalent weight of the acid ... 

Maleate/vinyl ether formulations based on a model unsaturated polyester prepared from maleic anhydride and 1,5-pentane diol and triethylene glycol divinyl ether were studied. At molecular weights of less than about 10,000 the cured films were extremely brittle. When the equivalent weight of the unsaturated polyester was increased by replacing some of the maleic anhydride with succinic anhydride, measurable values for film elongation could be obtained but the cure speed was definitely slower. When either diethyl maleate or isobutyl vinyl ether were added as monofunctional diluents the cure dose needed to obtain 200 MEKDR was increased and the flexibility measured by pencil hardness increased as the amount of diluent was increased. A urethane vinyl ether was synthesized and used to replace DVE-3 and films with increased elongation were obtained at equivalent at dosages as low as 1 J/cm2. 

The gram-equivalent weight (GEW) of a base is the mass of the base (in grams) that will provide 1 mole of hydroxide ions in a reaction or that will react with 1 mole of H+ ions. This problem can be done by using the factor-label method. 

For example, if there are 2.0 equivalents dissolved per liter, a solution would be referred to as 2.0 normal, or 2.0 N. The equivalent is either the same as the mole or some fraction of the mole, depending on the reaction involved, and the equivalent weight, or the weight of one equivalent, is either the same as the formula weight or some fraction of the formula weight. Normality is either the same as molarity or some multiple of molarity. Let us illustrate with acids and bases in acid-base neutralization reactions. 

The equivalent weight of an acid in an acid-base neutralization reaction is defined as the formula weight divided by the number of hydrogens lost per formula of the acid in the reaction. Acids may lose one or more hydrogens (per formula) when reacting with a base. 

As in Section 4.3, acid-base neutralization reactions will be illustrated here. In order to calculate the equivalent weight of an acid, the balanced equation representing the reaction in which the solution is to be used is needed so that the number of hydrogens lost per formula in the reaction can be determined. The equivalent weight of an acid is the formula weight of the acid divided by the number of hydrogens lost per molecule (see Section 4.3). 

Thus a one-to-one reaction is involved, and in fact, all reactions of EDTA with metal ions (most metals do react with EDTA) are one-to-one. Therefore, we will not be concerned with a formal scheme for determining equivalent weights, as we were with acid-base reactions. 

Basura, V. I., Chuy, C., Beattie, P. D. and Holdcroft, S. 2001. Effect of equivalent weight on electrochemical mass transport properties of oxygen in proton exchange membranes based on sulfonated a,j3,j3-trifluorostyrene (BAM) and sulfonated-styrene-(ethylene-butylene)-styrene triblock (DAIS-analytical) copolymers. Journal ofElectroanalytical Chemistry 501 77-88. 

Based on this new model for the morphology of Nafion, the dimensional variations of the scattering entities with water content were used in simple space filling calculations to estimate the cluster diameter, the number of sulfonate sites per cluster, and the number of water molecules per cluster. The results of these model calculations showed that, for a given equivalent weight, the cluster diameter. 

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