Base buffer

A mixture of acetic acid and sodium acetate is one example of an acid/base buffer. The equilibrium position of the buffer is governed by the reaction... 

The relationship between the pH of an acid-base buffer and the relative amounts of CH3COOH and CH3COO- is derived by taking the negative log of both sides of equation 6.43 and solving for the pH... 

Suppose now that the pH is controlled by a weak base buffer, the equilibrium being written BH B + H, where B signifies a neutral base. The apparent dissociation constant is = (H )[B]/[BH ]. Following the earlier argument, we obtain... 

Because the ionic product of water = [H ] [OH ] = 1.04 x 10" at 25°C, it follows that pH = 14 - pOH. Thus, a neutral solution (e.g., pure water at 25°C) in which [H j = [OH ] has a pH = pOH = 7. Acids show a lower pH and bases a higher pH than this neutral value of 7. The hydrogen ion concentrations can cover a wide range, from -1 g-ion/liter or more in acidic solutions to -lO" " g-ion/liter or less in alkaline solutions [53, p. 545]. Buffer action refers to the property of a solution in resisting change of pH upon addition of an acid or a base. Buffer solutions usually consist of a mixture of a weak acid and its salt (conjugate base) or of a weak base and its salt (conjugate acid). 

Used alone, base normally means a Bronsted base, base buffer See buffer. 

Use the seven-step strategy to calculate the pH of the buffer solution using the buffer equation. Then compare the amount of acid in the solution with the amount of added base. Buffer action is destroyed if the amount of added base is sufficient to react with all the acid.The buffering action of this solution is created by the weak acid H2 PO4 and its conjugate base HP04. The equilibrium constant for this... 

Yamada, A. Miyazaki, H. Chiba, Y. Konagai, M. 2005. High-efficiency Cu(InGa)Se2 solar cells with a zinc-based buffer layer. Thin Solid Films 480 81 503-508. 

Larina, L. Kim, K. H Yoon, K. H Konagai, M. Ahn, B. T. 2003. Thin film CIGS-based solar cells with an In-based buffer layer fabricated by chemical bath deposition. Edited by Kurokawa, K. Kazmerski, L. L. McNelis, B. Yamaguchi, M. Wronski, C. Sinke, W. C. Proceedings of 3rd World Conference on Photovoltaic Energy Conversion (IEEE Cat. No.03CH37497), Vol. 1. pp. 531-534. 

Acid-base buffers comprise both a weak acid or base and its respective salt. Calculations with buffers employing the Henderson-Hasselbach equation are introduced and evaluated, thereby allowing the calculation of the pH of a buffer. Next, titrations and pH indicators are discussed, and their modes of action placed into context. 

A buffer comprises (1) a weak acid and a salt of that acid, (2) a weak base and a salt of that base, or (3) it may contain an acid salt. We define an acid-base buffer as a solution whose pH does not change after adding (small amounts of) a strong acid or base . Sodium ascorbate is a favourite buffer in the food industry. 

Amino acids are separated in their native form on a sulphonated polystyrene resin using a system of sodium or lithium based buffers. Separation is effected by stepwise, rather than gradient elution, and the chromatography can be further optimized by carefully controlling the temperature of the analytical column. 

Acidity regulator/acid, alkali, base, buffer, buffering agent, pH adjusting agent... 

C—Both A and C are buffers, because they have conjugate acid-base pairs of either a weak acid (A) or a weak base (C). The weak acid buffer would have a pH below 7, and the weak base buffer would have a pH above 7. 

The primary characteristic of an acid/base buffer affecting steam requirements is the temperature dependence of Pgc /P O-Since PSC /P O of the citrate system is independent of temperature, the ideal minimum steam requirement (moles H20/moles SO2) of a simple stripper is equal to the ratio, °f the... 

Zacharis, E., Moore, B.D. and Hailing, P.J., Control of enzyme activity in organic media by solid-state acid-base buffers. J. Am. Chem. Soc., 1997, 119, 12396-12397. 

The selectivity is severely impeded if phosphate-based buffers are employed, since calcium-phosphate complexation occurs. In principle, the selectivity of a membrane-based ISE is constant, but contamination and degradation of the membrane s polymer component means that the selectivity decreases with usage. Contamination with biological samples can also be problematic. 

Clay minerals are important to the crustal-ocean-atmosphere fectory, not just for their abundance, but because they participate in several biogeochemical processes. For example, the chemical weathering reactions responsible for their formation are accompanied by the uptake and release of cations and, thus, have a large impact on the chemical composition of river and seawater. This includes acid/base buffering reactions, making clay minerals responsible for the long-term control of the pH of seawater and, hence, of importance in regulating atmospheric CO2 levels. 

Minimal Interactions with Assay Components. If a buffer binds to or reacts with a component of the system, it should be avoided. For example, borate buffers can complex with alcohols and carbohydrates and great care should be exercised when utilizing these compounds. Some arsenate-based buffers have oxidizing potential with respect to thiols. Buffers should also have a low binding capacity with respect to divalent cations. 

An excellent demonstration of the tunability of ionic liquids for catalysis is provided by an investigation of the dimerization of 1-butene (235). A Ni(cod)(hfacac) catalyst (Scheme 23) was evaluated for the selective dimerization of 1-butene after it was dissolved in various chloroaluminate ionic liquids. Earlier work on this reaction with the same catalyst in toluene led to the observations of low activity and difficult catalyst separation. In ionic liquids of varying acidity, little catalytic activity was found. However, a remarkable activity was achieved by adding a weak buffer base to an acidic ionic liquid. The reaction took place in a biphasic reaction mode with facile catalyst separation and catalyst recycling. A high selectivity to the dimer product was obtained because of a fast extraction of the Cg product from the ionic liquid phase, with the minimization of consecutive reaction to give trimers. Among a number of weak base buffers, a chinoline was chosen. The catalyst performance was compared with that in toluene. The catalyitc TOF at 90°C in toluene was... 

For many years, automated amino acid analyzer using lEC and postcolumn derivatization with nin-hydrin (or less frequently with fluorescamine) has been the most popular technique for amino acid determination. Amino acids are separated in their free form by employing stepwise elution with sodium- or lithium-based buffers. 

Although dated, the following example illustrates the fact that size-exclusion chromatography can be conducted efficiently and reliably under high pressure using a less conventional solvent system (TEAP) than the acetate-, phosphate-, and borate-based buffers described in the manufacturers catalogues 66 ... 

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