Titratable base number

Base number the quantity of acid, expressed in milligrams of potassium hydroxide per gram of sample, that is required to titrated a sample to a specified endpoint. 

Acid and Base Number by Color-Indicator Titration... 

Total Base Number of Petroleum Products by Potentiometric Perchloric Acid Titration... 

D 4739 D 4742 Base Number Determination by Potentiometric Titration. Oxidation Stability of Gasoline Automotive Engine Oils by Thin Film Oxygen Uptake (TFOUT)... 

Because of the striking color change between the bases (1) and monocations (4), it has been suggested that they could be useful indicators in acid-base titrations. A number of 2,4-disubstituted derivatives have been suggested for use over the pH range 5-9 (80MI2), and certain 3-aryl-... 

Numerous potentiometric titration-based chemical models have been proposed, a small number of which has been verified by H, and Al NMR and electrospray mass spectroscopic techniques. The models range in character relative to the number and nature of species considered, from simple (a small number of mononuclear monocitrate species) to inordinately complex (several mono- to trinuclear and mono- to tricitrate species). The models are incongruous, in that no two models are composed of the same species, nor do they predict similar Fe(III)-or Al-citrate aqueous speciation. Similarly, the models differ relative to the predicted impact of citrate on the solubility of Fe(III)- or Al-bearing accessory minerals. 

Similarly to the principle of acidic constituents, oil may, on occasion, contain alkaline or basic constituents. The presence of such constituents is determined through test methods for the base number. The relative amounts of these materials can be determined by titrating with acids. 

Samples of oil drawn from the crankcase can be tested to assess the reserve of alkalinity remaining by determining the total base number of the oil (ASTM D-664, ASTM D-2896, ASTM D-4739, IP 177, IP 276). Essentially, these are titration methods in which, because of the nature of the used oil, an electrometric instead of a color end point is used. The reserve alka-hnity neutralizes the acids formed during combustion. This protects the engine components from corrosion. However, the different base number methods may give different results for the same sample. 

Functionality. The number of carboxyl equivalents was determined from the potentlometrlc acid-base titration. The number molecular weight iii of the CTPnBA was determined by the Vapor Pressure Osmometer measurement. The product of the number of acid equivalents by the molecular weight divided by the weight of the titrated PnBA sample is the calculated average number of carboxyl groups per chain of the poly n-butyl acrylate. 

Base Number by Color-Indicator Titration ASTM D 664, Test Method for Acid Number of Petroleum Products by Potentiometric Titration or ASTM D 4739, Test Method for Base Number Determination by Potentiometric Titration. Neutralization numbers greater than 0.5 mg KOH per g of crude oil are likely to result in corrosion of carbon steel. Some prefer to use a neutralization number based on the distillate fraction present in the corrosive zone. This results in a critical neutralization number of about 1.5 mg KOH per g [79,20],... 

The measurement of acid number (or base number) during the course of a reaction. For example, in the production of polyester resins by the reaction of a glycol with maleic and phthalic acids, the total acid remaining is determined by titration of a weighed sample with potassium hydroxide using phenolphthalein as indicator. 

Total Acidity, Acid Number or Acid value, of a lubricating oil is the amount of titrating base, expressed as mg of KOH, required to neutralize all acidic constituents of 1 g of the sample. 

American Society for Testing and Materials, Base number of petroleum products by potentio-metric perchloric acid titration, D2896-96. West Conshohocken, PA 19428. 

One can write acid-base equilibrium constants for the species in the inner compact layer and ion pair association constants for the outer compact layer. In these constants, the concentration or activity of an ion is related to that in the bulk by a term e p(-erp/kT), where yp is the potential appropriate to the layer [25]. The charge density in both layers is given by the algebraic sum of the ions present per unit area, which is related to the number of ions removed from solution by, for example, a pH titration. If the capacity of the layers can be estimated, one has a relationship between the charge density and potential and thence to the experimentally measurable zeta potential [26]. 

The measurement of pK for bases as weak as thiazoles can be undertaken in two ways by potentiometric titration and by absorption spectrophotometry. In the cases of thiazoles, the second method has been used (140, 148-150). A certain number of anomalies in the results obtained by potentiometry in aqueous medium using Henderson s classical equation directly have led to the development of an indirect method of treatment of the experimental results, while keeping the Henderson equation (144). 

Now that we know something about EDTA s chemical properties, we are ready to evaluate its utility as a titrant for the analysis of metal ions. To do so we need to know the shape of a complexometric EDTA titration curve. In Section 9B we saw that an acid-base titration curve shows the change in pH following the addition of titrant. The analogous result for a titration with EDTA shows the change in pM, where M is the metal ion, as a function of the volume of EDTA. In this section we learn how to calculate the titration curve. We then show how to quickly sketch the titration curve using a minimum number of calculations. 

Sketching a Redox Titration Curve As we have done for acid-base and complexo-metric titrations, we now show how to quickly sketch a redox titration curve using a minimum number of calculations. 

Hydroxyl number and molecular weight are normally determined by end-group analysis, by titration with acetic, phthaUc, or pyromellitic anhydride (264). Eor lower molecular weights (higher hydroxyl numbers), E- and C-nmr methods have been developed (265). Molecular weight deterrninations based on coUigative properties, eg, vapor-phase osmometry, or on molecular size, eg, size exclusion chromatography, are less useful because they do not measure the hydroxyl content. 

Contaminant by-products depend upon process routes to the product, so maximum impurity specifications may vary, eg, for CHA produced by aniline hydrogenation versus that made by cyclohexanol amination. Capillary column chromatography has improved resolution and quantitation of contaminants beyond the more fliUy described packed column methods (61) used historically to define specification standards. Wet chemical titrimetry for water by Kad Eisher or amine number by acid titration have changed Httle except for thein automation. Colorimetric methods remain based on APHA standards. 

Because of the time and expense involved, biological assays are used primarily for research purposes. The first chemical method for assaying L-ascorbic acid was the titration with 2,6-dichlorophenolindophenol solution (76). This method is not appHcable in the presence of a variety of interfering substances, eg, reduced metal ions, sulfites, tannins, or colored dyes. This 2,6-dichlorophenolindophenol method and other chemical and physiochemical methods are based on the reducing character of L-ascorbic acid (77). Colorimetric reactions with metal ions as weU as other redox systems, eg, potassium hexacyanoferrate(III), methylene blue, chloramine, etc, have been used for the assay, but they are unspecific because of interferences from a large number of reducing substances contained in foods and natural products (78). These methods have been used extensively in fish research (79). A specific photometric method for the assay of vitamin C in biological samples is based on the oxidation of ascorbic acid to dehydroascorbic acid with 2,4-dinitrophenylhydrazine (80). In the microfluorometric method, ascorbic acid is oxidized to dehydroascorbic acid in the presence of charcoal. The oxidized form is reacted with o-phenylenediamine to produce a fluorescent compound that is detected with an excitation maximum of ca 350 nm and an emission maximum of ca 430 nm (81). 

Fig. 9. Genesis of acid tain (13). From the oxidation of C, S, and N during the combustion of fossil fuels, there is a buildup in the atmosphere (gas phase, aerosol particles, raindrops, snowflakes, and fog) of CO2 and the oxides of S and N, which leads to acid—base interaction. The importance of absorption of gases into the various phases of gas, aerosol, and atmospheric water depends on a number of factors. The genesis of acid rain is shown on the upper right as an acid—base titration. The data given are representative of the environment in the vicinity of Zurich, Switzedand.

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