Gram-milliequivalent Weight

The concentrations of electrolyte solutions are generally expressed in chemical units known as milliequivalents (mEq). The milliequivalent weight represents the amount, in milligrams, of a solute equal to 1/1000 of its gram equivalent weight. A milliequivalent is a unit of measurement of the amount of chemical activity of an electrolyte. A milliequivalent unit is related to the total number of ionic charges in solution and it takes the valence of the ions into consideration. Table 5.1 provides valence, atomic and milliequivalent weights, and formulae of selected ions. 

Active matter (anionic surfactant) in AOS consists of alkene- and hydroxy-alkanemonosulfonates, as well as small amounts of disulfonates. Active matter (AM) content is usually expressed as milliequivalents per 100 grams, or as weight percent. Three methods are available for the determination of AM in AOS calculation by difference, the two-phase titration such as methylene blue-active substances (MBAS) and by potentiometric titration with cationic. The calculation method has a number of inherent error factors. The two-phase titration methods may not be completely quantitative and can yield values differing by several percent from those obtained from the total sulfur content. These methods employ trichloromethane, the effects from which the analyst must be protected. The best method for routine use is probably the potentiometric titration method but this requires the availability of more expensive equipment. 

Written in this form, you see that the equivalents (or milliequivalents) of acid are equal to the equivalents of base. The equivalent weight of the acid is the grams of acid divided by the equivalents of base. The equivalent weight of monoprotic acid is equal to the molecular weight. The equivalent weight of diprotic acid is equal to half the molecular weight. 

Answer 5.3 Milliequivalent per liter. It is used to describe the concentration of ions dissolved in water. An equivalent is the number of grams that equal the respective ionic weight divided by the valency. 35.5 mg/1. 

A milliequivalent is the gram weight of a substance that will combine with or replace one milligram (one millimole) of hydrogen. A milliequivalent is 1/1000 of an equivalent weight. 

The term lEC means the number of ion-exchange groups, in the unit of milliequivalents, contained in one gram of dry resin. The term equivalent weight (EW) is also used for expressing the number of iou-exchange groups. 

The ion-exchange capacity of a resin k defined as the number of ion-exchange sites per weight equivalent of the column packing. It is typically expressed in terms of milliequivalent per gram resin (rnequiv/g). ... 

The standard electrolyte material in PEFCs belongs to the fully fluorinated Teflon -based family similar to that produced by E.I. DuPont de Nemours for space application in the mid-1960s. The membrane is characterized by its equivalent weight (inversely proportional to the ion exchange capacity). A typical equivalent weight range is 800 to 1100 milliequivalents per dry gram of polymer. The type used most often in the past was a melt-extruded membrane manufactured by DuPont and sold under the label Nafion No. 117. The perfluorosulfonic acid family of... 

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