Neutral point

Monofluorophosphoric Acid. Monofluorophosphoric acid (1) is a colorless, nonvolatile, viscous Hquid having practically no odor. On cooling it does not crystallize but sets to a rigid glass at —78°C. It has a density of = 1.818 g/mL. Little decomposition occurs up to 185°C under vacuum but it caimot be distilled. An aqueous solution shows the normal behavior of a dibasic acid the first neutralization point in 0.05 N solution is at pH 3.5 and the second at pH 8.5. Conductance measurements, however, indicate H2PO2F behaves as a monobasic acid in aqueous solution (59). The... 

Such a stationary value of V can be a relative maximum, a relative minimum, a neutral point, or an inflection point as shown in Figure B-1. There, Equation (B.1) is satisfied at points 1, 2, 3, 4, and 5. By inspection, the function V(x) has a relative minimum at points 1 and 4, a relative maximum at point 3, and an inflection point at point 2. Also shown in Figure B-1 at position 5 is a succession of neutral points for which all derivatives of V(x) vanish. A simple physical example of such stationary values is a bead on a wire shaped as in Figure B-1. That is, a minimum of V(x) (the total potential energy of the bead) corresponds to stable equilibrium, a maximum or inflection point to unstable equilibrium, and a neutral point to neutral equilibrium. 

The character of AV will determine the type of stationary value at x = Xi. Specifically, the dominant term in the Taylor series for AV must be examined in order to determine whether AV is always positive (a relative minimum), always negative (a relative maximum), sometimes negative and sometimes positive (an inflection point), or always zero (a neutral point). For AV to be positive, the leading term in the Taylor series, Equation (B.4), which is by inspection the largest term because h is a very small number, must be positive, i.e.. 

Electrical power systems are normally three-phase systems connected using wye or delta connections. In wye connections the three phases are connected to form a letter Y with a neutral point at the intersection of the three phases. In delta connections the three phases are connected to form a Greek letter delta (A). Delta systems do not have a neutral hence delta systems are 3-wire systems. A Y connection has a neutral and thus it is a 4-wire system. 

The common connection of all three armature windings in the Y connection allows a fourth, or neutral, conductor to be used. This neutral point is often grounded in transmission and distribution circuits. Such a circuit is termed a three-phase, four-wire circuit. 

If the total length of drill collar string would be, for example, 330 ft, then the number 232 ft would indicate the distance from the bit to the neutral point. 

This explains why heavy-weight drill pipe is successfully used for creating weight on the bit in highly deviated holes. However, in drilling a vertical or nearly vertical hole, a drill pipe must never be run in effective compression or, in other words, the neutral point must always reside in the drill collar string. 

Drillstring Failure Prevention. Drillstring failures are mainly due to vibrations, shocks and neutral point positioned too close to the drill pipes. They result in drillstring washouts and twist-offs. 

In the absence of sufficient hydrogen, the solubility of magnetite is markedly temperature dependent, which provides an explanation for some of the problems in high-temperature circuits. Most studies in boilers relate to high temperatures. Thus the work of Bloom " and of Potter and Mann has reproduced the types of corrosion found in high-pressure boilers. The relationship between corrosion rates and iron solubility and pH are given in Fig. 17.2. Note that the pH range about the neutral point (relative to 300 C... 

An excess of sodium carbonate promotes foaming during the distillation, and is to be avoided. Since the neutral point is not easily recognized with test paper, the carbonate is added in decreasing amounts, until, a fresh portion is no longer decomposed with gas evolution. 

Neutralizing capacity is not the only measure of a required amine feed rate. Once all acidic characteristics have been neutralized, amine basicity becomes the important issue because this raises the pH above the neutralization point, to a more stable and sustainable level. Consequently, in practice we are concerned with the level of amine necessary to raise the condensate pH to a noncorrosive level. This practical amine requirement is difficult to obtain from theoretical calculations because it must take account of the amine volatility, DR, and the boiler system amine recycling factor (as well as temperature). As noted earlier, the basicity of an amine has little or no relationship to its volatility or DR, so that reliable field results are probably a more important guide in assessing the suitability of an amine product than suppliers tables. 

Principle. By means of potentiometric titration (in nonaqueous media) of a blend of sulfonic and sulfuric acids, it is possible to split the neutralization points corresponding to the first proton of sulfuric acid plus that of sulfonic acid, and to the second proton of sulfuric acid. The first derivate of the titration curve allows identification of the second points the corresponding difference in the volume of titrating agent is used as a starting point in the calculation method (Fig. 4). 

As a result of this, the conductivity of the solution falls and continues to fall with each subsequent addition of alkali until the end-point is attained. On addition of a little sodium hydroxide after the neutralization point, there will be a small concentration of OH ions and conductivity will once again rise, this being the result of OTT ions having the second greatest mobility. The point corresponding to the minimum conductivity represents, therefore, the end-point of titration. 

On the basis of the Henderson equation for titration of acid or base one can prove mathematically that the half-neutralization point represents a true inflection point and that as the titration end-point dpH/dA is maximal or minimal, respectively (the latter is only strictly true for titration of a weak acid with a weak base and vice versa). 

The above solvents theory (A) and proton theory (B) have shown that in theory the neutrality point (of the pure solvent) lies for the amphiprotic solvents at pH = pKs and for the aprotic protophilic solvents at a pH somewhere between the highest acidity (of the protonated solvent) and an infinitely high pH. However, the true pH of the neutrality point of the solvent can only be obtained from a reliable pH measurement and the problem is whether and how this can be achieved. For water as a solvent, the true pH = - logaH+ = colog aH+ is fixed by the internationally adopted convention E°m ( H2(latm) = 0... 

In practice, the volume of titrant is plotted instead of the titration parameter, a. At the titration end-points Ej and E2, the volumes of titrant consumed indicate the respective amounts of the acids, while their pH values or better the pH heights around the half-neutralization points, h.n.p and h.n.p2, are related to the identities of the acids. Therefore, in the two-dimensional figure the abscissa represents the quantitative aspects and the ordinate the qualitative aspects. 

The subsequent text will be restricted to aqueous solutions and concentrations will be used instead of activities. Thus, the neutral point is given by the condition [H20+] = [OH ] = K J12,... 

Water. The pH range that can reasonably be used extends from 0 to 14, with the neutral point at pH 7. A solution with pH <7 is acidic and with PH >7 is basic. The commonest strong acids are HC104, H2S04, HC1 and HN03 strong bases include alkali metal and tetraalkylammonium hydroxides. 

Since this is the titration of a strong base by a strong acid, at the neutralization point, pH = 7.00. This is a solution ofBaCl2(aq), in which neither ion hydrolyzes. 

When an acid in solution is exactly neutralized with a base the resulting solution corresponds to a solution of the salt of the acid-base pair. This is a situation which frequently arises in analytical procedures and the calculation of the exact pH of such a solution may be of considerable importance. The neutralization point or end point in an acid-base titration is a particular example (Chapter 5). Salts may in all cases be regarded as strong electrolytes so that a salt AB derived from acid AH and base B will dissociate completely in solution. If the acid and base are strong, no further reaction is likely and the solution pH remains unaffected by the salt. However if either or both acid and base are weak a more complex situation will develop. It is convenient to consider three separate cases, (a) weak acid-strong base, (b) strong acid-weak base and (c) weak acid-weak base. 

A definition of the point of neutralization in words says, at the neutralization point, the number of moles of acid equals the number of moles of hydroxide . We re-express the definition as... 

Litmus often looks purple-grey at the neutralization point. This colour tells us we have a mixture of both the red and blue forms of litmus. 

---