Gram equivalent

The conductivity of a solution containing 1 gram equivalent of solute when measured between two large parallel electrodes at a distance of 1 cm apart is called the equivalent conductivity A. 

The number of grams in a sample divided by the number of equivalents in the same sample gives the gram-equivalent weight of the material. 

Faraday s law states that 96,487 coulombs (1 C = 1 A-s) are required to produce one gram equivalent weight of the electrochemical reaction product. This relationship determines the minimum energy requirement for chlorine and caustic production in terms of kiloampere hours per ton of CI2 or NaOH... 

Effect of Fiber Properties. Acid dyes are attracted to the accessible amine ends of the nylon chains located in the amorphous regions of the fiber. Acid dye affinity of nylon can be adjusted by a dding excess diamine or diacid to the polymer salt or by changing the molecular weight in polymerization. A light acid-dyeable nylon-6,6 is spun with 15—20 amine ends, expressed in terms of gram equivalents per 10 g of polymer. A medium or... 

According to Faraday s law, one Faraday (26.80 Ah) should deposit one gram equivalent (8.994 g) of aluminum. In practice only 85—95% of this amount is obtained. Loss of Faraday efficiency is caused mainly by reduced species ( Al, Na, or A1F) dissolving or dispersing in the electrolyte (bath) at the cathode and being transported toward the anode where these species are reoxidized by carbon dioxide forming carbon monoxide and metal oxide, which then dissolves in the electrolyte. Certain bath additives, particularly aluminum fluoride, lower the content of reduced species in the electrolyte and thereby improve current efficiency. 

Faraday s Law of electrolysis states that the amount of chemical change, ie, amount dissolved or deposited, produced by an electric current is proportional to the quantity of electricity passed, as measured in coulombs and that the amounts of different materials deposited or dissolved by the same quantity of electricity are proportional to their gram-equivalent weights (GEW) defined as the atomic weight divided by the valence. The weight in grams of material deposited, IF, is given by... 

Cathode Efficiency. Faraday s law relates the passage of current to the amount of a particular metal being deposited ie, 96,485 coulombs, equal to one Faraday, deposits one gram-equivalent weight of a metal at 100% efficiency. The cathode efficiency, an important factor in commercial electroplating, is the ratio of the actual amount of metal deposited to that theoretically calculated multipHed by 100%. 

Gram-Fkrbung, /. (Bact.) Gram staining. Gramm-aquivalent, n. gram equivalent. 

One gram-equivalent (or pound-equivalent) represents the mass in grams (or pounds) of a material that is numerically equal to its equivalent weight. 

The material changes in the cell are completely defined when we know the quantity of electricity passing through, for Faraday s law teaches us that for a quantity F there will always be a gram-equivalent of chemical change, independent of the electromotive force. 

Equivalent weight or gram equivalent, a mole divided by the valency of the substance. Example a mole of sodium chloride — 58.45 g, valency = 1, therefore equiv. wt = 58.45. A mole of calcium carbonate = 100.08 g, valency = 2, therefore equiv. wt. = 50.04. 

Milliequivalent or gram milliequivalent (mEq) unit of mass being one thousandth of a gram equivalent. 

All velocity constants are expressed in (gram equivalents/liter)- sec. ... 

It is convenient to express the rate constants in units of gram equivalents of the reacting functional group (COOH in this case) per liter, rather than in moles of the reactant per liter as is customary this scheme has been adopted in Table V. Then the rate of the first and second steps may be written, respectively... 

It is not usual to talk about the resistance of electrolytes, but rather about their conductance. The specific conductance (K) of an electrolyte is defined as the reciprocal of the resistance of a part of the electrolyte, 1 cm in length and 1 cm2 in cross-sectional area. It depends only on the ions present and, therefore it varies with their concentration. To take the effect of concentration into account, a function called the equivalent conductance, A, is defined. This is more commonly (and conveniently) used than the specific conductance to compare quantitatively the conductivities of electrolytes. The equivalent conductance A is the conductance of that volume of the electrolyte which contains one gram equivalent of the ions taking part in the electrolysis and which is held between parallel electrodes 1 cm apart (units ohm-1 cm4). If V cubic centimeters is the volume of the solution containing one gram equivalent, then the value of L will be 1 cm and the value of A will be V square centimeters, so that... 

In aqueous solutions, concentrations are sometimes expressed in terms of normality (gram equivalents per liter), so that if C is concentration, then V = 103/C and a = 103 K/C. To calculate C, it is necessary to know the formula of the solute in solution. For example, a one molar solution of Fe2(S04)3 would contain 6 1CT3 equivalents cm-3. It is now clear as to why A is preferred. The derivation provided herein clearly brings out the fact that A is the measure of the electrolytic conductance of the ions which make up 1 g-equiv. of electrolyte of a particular concentration - thereby setting conductance measurements on a common basis. Sometimes the molar conductance am is preferred to the equivalent conductance this is the conductance of that volume of the electrolyte which contains one gram molecule (mole) of the ions taking part in the electrolysis and which is held between parallel electrodes 1 cm apart. 

It may be pointed out that for uni-univalent electrolytes the values of a and am are identical since the gram equivalent weight and the gram molecular weight are the same. In the case of uni-bivalent and bi-univalent electrolytes the a value is half the am value since the equivalent weight of such compounds is half the molecular weight. 

If the resistance of any other electrolyte is found by measurement to be Rx when using the same conductance cell, then the specific conductance of this electrolyte is L1/ . Thus, on multiplying the value of specific conductance so obtained by V, the volume of solution in milliliters containing one gram equivalent weight of the electrolyte under investigation, the equivalent conductance A is calculated. 

In the relationship shown above, A and B are constants depending on temperature, viscosity of the solvent, and dielectric constant of the solvent, C is the concentration expressed in gram equivalents per liter, and Ac represents the equivalent conductance of the solution. A0 is the equivalent conductance at infinite dilution - that is, at C = 0, when the ions are infinitely apart from one another and there exists no interionic attraction, a represents the degree of dissociation of the electrolyte. For example, with the compound MN... 

Thus, the charge of an electron is equal but opposite to that carried by a hydrogen ion. The calculated result of the quantity of electricity carried by a single ion shows that where the gram-ionic weight of an ion is numerically identical with the gram-equivalent, that is when the ion is univalent, the ion carries a charge equal to that of an electron. It can be... 

Calculate the number of gram-equivalents of solute in 0.500 liter of a 3.00 N solution. 

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. 

D) Use the relationship gram-equivalents acid = gram-equivalents base. Solve for the gram-equivalents of acid. 

At neutralization, the gram-equivalents of acid = the gram-equivalents of base. Therefore,... 

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. 

It is also sometimes simply referred to as the gram-equivalent . However, GEW has two distinct definitions for neutralization as well as as oxidation-reduction reactions as stated below ... 

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