Oxygen equivalent weight

In 1817 Dobereiner found that if certain elements were combined with oxygen in binary compounds, a numerical relationship could be discerned among the equivalent weights of these compounds. Thus when oxides of calcium, strontium, and barium were considered, the equivalent weight of strontium oxide was approximately the mean of those of calcium oxide and barium oxide. The three elements in question, strontium, calcium, and barium were said to form a triad. 

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. 

The effects of equivalent weight (FW = g polymer/mol SO3H) and water content on diffusion coefficient, solubility, and permeability of oxygen for fully hydrated BAM, S-SEBS, ETFE- -PSSA, Nafion 117, and BPSH membranes have been studied. It has been found that the diffusion coefficients of all the studied membranes decrease with increasing EW, while the solubility correspondingly increases. These trends are the same as found in... 

Biichi, F. N., Wakizoe, M. and Srinivasan, S. 1996. Microelectrode investigation of oxygen permeation in perfluorinated proton exchange membranes with different equivalent weights. Journal of the Electrochemical Society 143 927-932. 

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. 

Potassium hydrogen phthalate has many uses in analytical chemistry. It is a primary standard for standardization of bases in aqueous solutions. Its equivalent weight is 204.2. It also is a primary standard for acids in anhydrous acetic acid. Other applications are as a buffer in pH determinations and as a reference standard for chemical oxygen demand (COD). The theoretical COD of a Img/L potassium hydrogen phthalate is 1.176mg O2. 

Equivalent Weight. The equivalent wt of an element is the wt that will combine with. or react with or can replace one atomic wt of hydrogen or one half atomic wt of oxygen. 

Five grains of anhydrous strontium nitrate (or the equivalent weight of the 4-hydrate) are dissolved in 50 ml of 3% hydrogen peroxide and mixed with a solution of 7 ml of concentrated aqueous ammonia in 100ml of water. The peroxide 8-hydrate is converted to the anhydrous compound by heating it at 300 C for about 4 hours in dry CCh-free oxygen, as described under the procedure for barium. 

In BOD measurement, the sample volume is usually 300 mL. The milli-equivalent weight for oxygen is 8000. 

It was found in an experiment that an electric current passing through a series of cells deposited 10.78 g of silver, 6.967 g of bismuth, and 3.178 g of copper, and liberated 0.560 liter of oxygen and 1.12 liters of chlorine, at standard conditions. Calculate the equivalent weight of each of these elements, except oxygen, from these data. 

The equivalent weight and molecular size data indicate that marine humic substances are approximately 900-1200 daltons and are composed of two to four fatty acid chains (Harvey and Boran, 1982b). The key to the pathway (Fig. 1) is in the NMR spectra in that all the marine fulvic acids and marine humic acids had 79-94% methyl and methylene protons and 2-24% protons on oxygenated carbon. The question then posed was What hydrocarbonlike class of compounds, present in all marine environments, is capable of... 

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