Concentration expression normal solution

The second approach is to use a specified concenfration of solution. This concentration is normally expressed as a hectolitre concentration and is the grams or milliliters of formulated product per 100 L of water. Here the trees are sprayed until run-off (the point at which the droplets coalesce and start to drip from the leaves). Once this point has been reached, the trees cannot be overdosed, since any additional solution will fall from the trees. This method, therefore, gives the advantages of (a) not overdosing, (b) tree size is irrelevant, and (c) no calculation of tree numbers is required. 

Normality a way to express the concentration of a solution, the number of equivalents per liter of solution... 

At this point let us address the problem of expressing abundance of compounds in a bulk phase. In environmental chemistry, the most common way to express concentrations is not by mole fraction, but by the number of molecules per unit volume, for example, as moles per liter of solution (mol L, M). This molar concentration scale is sometimes not optimal (volumes are, for example, dependent on Tandp, whereas masses are not hence, the use of concentration data normalized per kilogram of seawater is often seen in the oceanographic literature). However, the molar scale is widely used. We can convert mole fractions to molar concentrations by ... 

Molar concentration and normality are expressed in a specific amount of solute per a fixed volume of solvent. Both of these can be expressed in terms of the amount of solute by algebraic manipulation. 

Equation 5.15, as the foregoing proves, is a solution to Eq. 3.42. Furthermore, it becomes infinitely narrow at t = 0 and thus acquires the necessary 6-function form at the beginning. It can be shown that this expression normalizes to unit area (which means it applies to one mole of component, or one molecule if one chooses this unit of concentration, per unit area of cross section) when the constant in Eq. 5.15 equals (47r )) 1/2. Thus the normalized Gaussian profile is... 

It is common not to use mole fraction as the measure of concentration in solutions, but rather to express the concentration of species in terms of molalities or molarities. The former is defined as the number of moles in a kg of solvent and the latter is defined as the number of moles per liter of solution (- concentration). Since the molality is obviously temperature independent, it is the normal concentration measure used, and our convention for activity coefficient is now ps = p + F / ln ysxs for the solvent where the subscript s signifies solvent and ys - 1 when xs - 1, and for the solute p, = pf + RTlnyimi where y, - 1 as m, - 0. If there is more than one component, then the concentrations of all solutes must fall to zero simultaneously if the formula is to have any meaning, and it would be more correct to write y -> 1 as xs - 1. (Different symbols were recommended by the IUPAC for the activity coefficients, i.e., fi, yi and y, or yx, ym>, and yc>, when the concentration is expressed by mole fraction, molality and amount concentration (molarity), respectively, however, mostly y is used.)... 

In this expression, is the concentration of the solute in mole fraction units, and //j is its chemical potential in the standard state, i.e., when jc, assumes a standard or normalized value of unity... 

Equivalent concentration and normality. This method of expressing concentrations is analogous to molar concentrations, with the solute expressed in terms of equivalents. One problem that is often encountered is the conversion of a molar concentration to equivalent concentration. Let [C] be the molar concentration of any substance, where the symbol [ ] is read as the concentration of. Convert this to equivalent concentration. 

As discussed in Chapter 1, concentrations are normally expressed in the oceanographically convenient form of moles of solute per kilogram of solution (molkg ) or in molar (m) units. Because activity coefficients are dimensionless correction factors, they are equally applicable to all concentration units. 

Likewise, a one normal solution contains 1 g equivalent weight of solute in 1L of solution for example, 1 mol HCl, 0.5 mol H2SO4, and 0.33 mol H3PO4, each in IL of solution, are one normal solutions. The use of normality is limited in that a given solution may have more than one normality, depending on the type of reaction for which the solution is used. The molarity of a solution, however, is a fixed number because there is only one molecular mass for any substance. Normality is no longer recommended to express concentrations. Nevertheless, the term is included here because it remains in common usage and is related to the equivalent concept sometimes favored for serum electrolyte concentrations in the United States and some other countries. 

Normality The concentration of a solution expressed as the number of equivalence per one liter of solution. 

There are various ways of expressing the coneentration of a solution containing a solute (dissolved) in a solvent, e.g., a pollutant in a water (wastewater) stream. Solutions may be either dilute or concentrated. When a solution contains a relatively small quantity of the solute, it is dilute when the amount of solute is large, the solution is said to be concentrated. The precise quantity of solute contained in a given amount of solution is called the concentration. The latter may be designated in physical units as in weight or mole percent or it may be expressed in terms of chemical units as in molar and normal solutions. 

The concentration of a solute is usually expressed as the amount of a solute in a unit volume of a solution. The amount of a solute can be in grams (g), kilograms (kg), moles (mol), or normals (n). The unit volume of a solution is always in litres (1). A... 

The volumetric scales of concentration are those, like molar concentration and normality, in which the concentration is expressed as the amount of solute per fixed volume of solution. When the concentration is expressed on a volumetric scale, the amount of solute contained in a given volume of solution is equal to the product of the volume and the concentration ... 

Problem 3.6 When analyzing the thermodynamic properties of polymer solutions, it is sufficient to consider either the solvent or the solute, and for reasons of simplicity the former is normally considered. Moreover, for many physicochemical calculations, especially when dealing with dilute solutions, it is convenient to express the solvent activity as a power series in terms of polymer concentrations C2 in mass/volume units. Therefore, starting with Eq. (3.12), express the difference in chemical potential of the solvent in the solution and in the pure state, i.e., (pi -p ), in terms of the mass concentrations of the solute in dilute solutions. 

Environmental objectives are normally not well defined because economic objective functions normally involve profitability measures, whereas the value of reduced pollution is not easily quantified by economic measures. As a consequence, design teams often formulate mixed objective functions that attempt to express environmental improvements in financial terms. In other cases, the team may settle for the optimization of an economic objective function, subject to bounds on the concentrations of the solutes in the waste streams. It is important to assess whether the constraints are hard (not allowed to be violated) or soft (capable of being violated under unusual circumstances). Emphasis must be placed on the formulation of each constraint and the extent to which it must be honored. 

Gay-Lussac improved the design of these devices and was the first to use the names burette, pipette, and normal solution (Figure 4). The latter term did not mean what it means now but only a solution of a given concentration. At the time the concentration of titrants used in various determinations was chosen arbitrarily, so that the volume of titrant consumed by a certain amount of sample indicated directly the quality, expressed in arbitrary degrees. Some of the degrees used then still remain in use, for example, those used for water hardness . 

For the rectangular element shown in Figure 4.1, the solution of eq. (4.19) is subjected to proper boundary conditions given in Appendix A for a particular case, which includes detailed analytical procedures for deriving two suitable solutions. From Appendix A, the normalize concentration expression for concentration polarization care(C oo = C > C o) is... 

Similarly, the solution of eq. (Al) for activation polarization (Co < Cb) upon using the boundary conditions given below as weU as eqs. (A6) and (A8) yields the normalized concentration expression... 

Again, as expected, the equivalent conductance changes with concentration. However, it was noted by early investigators that for dilute (less than about 0.1 normal) solutions, A varied with the square root of the concentration, and the y-intercept of the straight line of A versus /n was a value of A that was characteristic of the ionic solute. This characteristic, infinitely diluted value is given the symbol Aq. Various values of Ag are listed in Table 8.4. Mathematically, the relationship between the equivalent conductance versus concentration can be expressed as... 

The solution of A is called the titrand solution, and that of B is the titrant solution. In some countries (France, for example), a solution is called titrated if it contains a known amount of substance in a known volume. The titer of a solution is the reactant proportion (and thus the solvent proportion) in the solution. In the largest sense, it means its concentration (see Chap. I). In a more restrictive sense, it is the solute concentration expressed in mol/L or its normality (see Sect. 7.3). 

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