Conversion Formulas for Concentration

Conversion Formulas for Concentration of Solutions Electrochemical Series... 

Table 1. Conversion Formulas for Various Concentration Units... 

TABLE 11.5 Conversion Formulas for Solutions Having concentrations expressed in Various Ways... 

Here is a short example showing this. For the titration of 25 mL of sulfuric acid, 20.35 mL of sodium hydroxide solution (0.1 mol L ) is consumed. We are looking for the concentration of the acid. The conversion formula for this is... 

Umrechnungsformeln fiir verschiedene Konzentrationen — Conversion formulae for different concentrations... 

If component Q is also important for the conversion rate, the concentration Ca can be introduced in the formulae for. An, and An0 in a similar way as CP. Hence, it is concluded that calculating the effectiveness factor for multimolecular reactions is basically not very different than for simple reactions (if the proper Aris numbers are used). 

An absolutely annoying feature of dealing with chemical compounds is that their concentration may be expressed either in (1) ppm and ppb or (2) mg/m (milligrams per cubic meter). Tables expressing concentration data in ppm or ppb cannot be interchanged with tables expressing the same data in mg/m . Luckily, there is a formula for converting one form of measurement into the other. The conversion formula is... 

To convert between units of radon-222 radioactivity (Ci or Bq) and the potential alpha energy concentration (WL or J/m the equilibrium between radon gas and radon daughters must be known (See Chapter 9 for conversion formula). When radon is in equilibrium with its progeny, that is, when each of the short-lived radon daughters is present at the same activity concentration in air as radon-222, then 1 WL equals 100 pCi radon-222/L of air. However, when removal processes other than radioactive decay are operative, such as with ventilation, the concentration of short- lived daughters will be less than the equilibrium amount. In such cases an equilibrium factor (F) is applied. For example, if the equilibrium factor is 0.5, then 200 pCi radon-222/L of air is equivalent to 1.0 WL if the equilibrium factor is 0.3, then 1 WL corresponds to 333 pCi radon-222/L of air. 

The Kubelka-Munk type is designed for spectra that are measured in diffuse reflectance. The spectral intensities in Kubelka-Munk units are more linear in concentration than those in absorbance units. The conversion formula is... 

The mathematical relation becomes rather complicated for reactions with a more complex stoichiometry such as the reaction of Fe " ions with I ions mentioned above. For better overview, it would be advisable in this case to create a kind of table (Table 6.1). For each substance involved, the table lists in the first row the standard value of its chemical potential for calculating the drive of the reaction under standard conditions. In the following, we assume that at the begiiming of the reaction, Fe " and I both have a concentration of Cq and that Fe " and I2 are absent. The concrete values of the initial concentrations of the substances follow in the next row. Finally, the formulas for the concentrations at an arbitrary time t are listed which can be calculated by using the stoichiometry of the reaction, is the density of conversion mentioned above. 

It immediately follows from the conversion formula that the concentration of the base formed by the proton transfer from the acid to the water is equal to that of the resulting oxonium ions, c Bs) = CrCHsO" ). If we furthermore assume that the acid of the weak acidic pair is only slightly dissociated, the undissociated portion Ci.(Ad) can, in first approximation, be equated to the initial concentration Cq, Cr(Ad) Co,r- When both terms are inserted into Eq. (7.5) and this equation is solved for RT In Cj-CHsO" ), we obtain... 

The last formula is valid for concentration expressed in any units, as the conversion factor reduces, so... 

Another method is also widely used experimental data are used to plot the dependence/x)- / corresponding to this or another reaction order, e.g., log(x) - / for = 1 or x - / for n = 2. The rectification of data by one of these plots is considered as an evidence for the corresponding reaction order. Table 1.1. contains the formulas for kinetic curves of reactant A, which enters into the reaction of the type n A Products and nAA + nsB Products. Note that, for the reliable determination of the reaction order from the shape of the kinetic curve, it is necessary that the reaction had occurred to a sufficient depth. For example, the reaction of order I can be distinguished from the reaction of order II if the reaction conversion 1 - x considerably exceeds (2dx), where dx is the error in measurement of the reactant concentration at X = 2% it is needed that x < 0.8, i.e, the conversion would exceed 20%. 

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