Molality, mean

Figure 1 (left). Comparison of SDM Davies Technique and LCM in Predicting Molal Mean Activity Coefficient (1-2 electrolyte) at 25°C. Data from Robinson and Stokes (24). 

T" 0,1 MPh or 101,32, kPa x mole fraction, m molality, mean ionic molality White I and Sn arc ihc Standard Stale solid phases lor these twit chemical elements. 

I I electrolyte, HCI Concentration, molal Mean activity coefficient 2 1 electrolyte, CaClj Concentration (moles dm ) Mean activity coefficient 2 2 electrolyte, CdSO Concentration, molal Mean activity coefficient... 

The word molality means the amount of solute divided by the mass of the solvent. The usual units are mol kg L for-which the symbol m is frequently used to avoid confusion with the symbol for metre, it is best to use italics. 

Mean physiological setting point of active molality for background calibration (minimum active molality) Mean active molality for calibration Allowable error in % Undiluted specimen s Diluted sample (1 + 19)... 

Table t Values Fit for Molality Mean Ionic Activity Coefficient Data of Aqueous Electrolytes at 298,15 K... 

Molality means moles of solute per kilogram of solvent. ... 

The following data (for 25°C) were obtained at the pzc for the Hg-aqueous NaF interface. Estimate and plot it as a function of the mole fraction of salt in solution. In the table,/ is mean activity coefficient such that a = f m , where m is mean molality. 

The activity of an ion is related to its molality through the mean activity coefficient 7+ therefore... 

Sometimes tabulated values of the mean molal heat capacities Cp (T) are more easily accessible than C (T data, with respect to a reference temperature of T = 25°C (see Table 2-45). Since Cp is defined over the range T and T, by... 

Mean Molal Heat Capacities of Gases Between 25°C and T°C (Reference pressure = 0)... 

In the event the mean molal heat capacity data are available with a reference temperature other than = 25°C (see Table 2-46 for data with = 0°C), the following equation can be used to calculate AH (Tj) ... 

An alternative representation is useful when data on mean molal heat capacities Cj (T) are available with 25 C as the reference temperature (T ). Then the equation... 

Method 3. Use mean molal heat capacity data from Table 2-46 with reference conditions of 0°C and 1 atm. Then the equation for T, is... 

Table 21.9 Stoichiometric mean molal activity coefficients (7,) for aqueous inorganic...

Let x and x denote the mole fractions of the two sparingly soluble solids in their respective saturated solutions let y and y denote their mole ratios, m and ml their molalities, and a and a their activities on the molality scale. If the saturated solutions are sufficiently dilute, we may, with sufficient accuracy, neglect the differences between the four ratios x/x, y/yf, m/m, and a/a. We can express the difference between the cratic terms by means of any of these quantities, thus,... 

Suppose that we arbitrarily set the partial molal entropy of the K+ ion equal to zero. This means that we assign to the Cl- ion the whole of the partial molal entropy of the ion pair (K+ + Cl-) that is to say, we assign to the Cl- ion, not only the unitary term for the Cl- ion, but also the cratic term for both ions, and also the unitary term for the potassium ion. 

E6.12 The HC1 pressure in equilibrium with a 1.20 molal solution is 5.15 x 10 8 MPa and the mean ionic activity coefficient is known from emf measurements to be 0.842 at T = 298.15 K. Calculate the mean ionic activity coefficients of HC1 in the following solutions from the given HC1 pressures... 

Although the data are not plentiful, it is clear that the hydrothermal solutions of sediment-hosted ridges and back-arc basin covered by sediment (Okinawa Trough) contain high amounts of ammonium (2.8-13.6 p.molal) (Scott, 1997). This means that ammonium was derived by thermal maturation reaction of organic matter in sediments by the following reactions (Gamo et al., 1991),... 

The molality, m = moles per kilogram of solvent, as a temperature-independent concentration unit instead of the molarity, C = moles per litre of solution this means that the amount of solvent and hence its number of moles is fixed. 

The mean molality values m (moles per kilogram), mole fractions x (dimensionless number) and concentrations c (moles per cubic decimetre) are related by equations similar to those for non-electrolytes (see Appendix A). 

Fig. 1.1 The activity coefficient y of a nonelectrolyte and mean activity coefficients y of electrolytes as functions of molality...

If the validity of Eq. (1.3.31) is assumed for the mean activity coefficient of a given electrolyte even in a mixture of electrolytes, and quantity a is calculated for the same measured electrolyte in various mixtures, then different values are, in fact, obtained which differ for a single total solution molality depending on the relative representation and individual properties of the ionic components. 

The cost of refrigerant is 11.5 GJ 1, the mean molal heat capacity of the vapor is 40 kJ kmol-1K-1, and the latent heat of acetone is 29,100 kJ kmol-1. 

Here, we have represented the activities of aqueous species with the product y m of the species activity coefficients and molalities, according to Equation 3.6. The symbol IT in this equation is the product function, the analog in multiplication to the summation . Table 3.2 lists the meaning of each variable in this and following equations. 

To determine freezing point depression, we first need molality, which means we need mass of solvent. 

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