Effective Volume Measurement

simple, and practical method for pore volume measurement was proposed 

1 (EMD) Regular EMD made by the clcctrodeposi-tion on a Ti anode from MnS04 + H2S04 solution (pore diameter is 50A) 45.0 48.2 58.0 16.9 

8 (CMD) Chemical Mn02 prepared by the thermal decomposition of MnCO, with additional process to deposit y - Mn02 (pore diameter is 7()A) 45.0 92.8 94.3 1.6 

IBA No. 15 (EMD) Dense EMD deposited from a suspension bath of MnS04 solution the pore size is considerably finer than regular EMD, such as IC No. 1 25.0 30.0 48.0 37.5 

IBA No. 27 (NMD) Natural ore from Mexico excellent for carbon-zinc cells 17.5 27.0 30.0 10.0 

From the variation of the volume of the EMD vs the amount of added water, the effective pore volume (EPV) is obtained as shown in Eigure 4.19. 

An industrial quantity of high-purity EMD is now being produced for alkaline Mn02-Zn cells. Therefore, EMD is an excellent source of future cathode materials (Lio,3Mn02 and IiMn204) for rechargeable lithium batteries. EVs need large 

---

Liquids have relatively low compressibility compared with gases and, thus, the mobile phase velocity is sensibly constant throughout the column. As a consequence, elution volumes measured at the column exit can be used to obtain retention volume data and, unless extreme accuracy is required for special applications, there is no need for the retention volume to be corrected for pressure effects. 

Figure 18. Procedure for EPV (effective pore volume) measurement (a) a 50 g MnO, sample is placed in a 100 mL graduated cylinder (2) water is added gradually in 0.5 mL portions (3) with a stopper in place, the cylinder is turned upside down 10 times while being shaken (4) the cylinder is droppes 4 cm onto a wooden surface (5) the Mn02 sample volume is read after 5 and 10 taps (i.e., drops).

The Effect of Solvent Composition on Retention Volume Measurement... 

Scheraga-Mandelkern equations (1953), for effective hydrodynamic ellipsoid factor p (Sun 2004), suggested that [rj] is the function of two independent variables p, the axial ratio, which is a measure of shape, and Ve, the effective volume. To relate [r ] to p and Ve, introduced f, the frictional coefficient, which is known to be a direct function of p and Ve. Thus, for a sphere we have... 

Similarly, concepts of solvation must be employed in the measurement of equilibrium quantities to explain some anomalies, primarily the salting-out effect. Addition of an electrolyte to an aqueous solution of a non-electrolyte results in transfer of part of the water to the hydration sheath of the ion, decreasing the amount of free solvent, and the solubility of the nonelectrolyte decreases. This effect depends, however, on the electrolyte selected. In addition, the activity coefficient values (obtained, for example, by measuring the freezing point) can indicate the magnitude of hydration numbers. Exchange of the open structure of pure water for the more compact structure of the hydration sheath is the cause of lower compressibility of the electrolyte solution compared to pure water and of lower apparent volumes of the ions in solution in comparison with their effective volumes in the crystals. Again, this method yields the overall hydration number. 

After the mould has closed, but before final clamping, a measured quantity of rubber is injected into the transfer port. The rubber forces the transfer port open until it contains the required volume. With a top injection system the mould is forced downwards and the transfer piston remains stationary. With a bottom injection unit the mould is stationary and the transfer piston is raised. In both cases the effective volume of the port is increased by the filling action of the rubber. 

Systematic errors usually arise from specific shortcomings in the measuring instrument, the observer, or the way in which the measurement is taken. Sources of systematic error include a badly calibrated measuring device, a faulty instrument movement, an incorrect action by the experimenter (e.g., misreading a volume measurement), or the parallax effect when incorrectly viewing a scale. Repeating the measurement does not necessarily help, because the error may be repeated, and the analyst may... 

The concept of a theoretical plate is based on the number of equilibria that may have taken place during the separation process and this number is related to the number of times the effective volume of a column is greater than the peak volume. The variance (a2) for the peak is a measure of the broadening of the injection volume while the square of the retention time (fR2) is a measure of the effective column volume for that compound. Hence the number of theoretical plates (AO may be calculated from the following equation ... 

Closing volume measurement, 29S-96 Colorimetric analysis for air monhoriqg, 262-64,27S to measure nitrogen oxides, 269 Community Health Effects Surveillance Studies (chess), 9,432 Concentration. See Ozone otmcentration Feroi aoetyliiitrate concentration Photochemical-oxidant concentration... 

Alhedai et a also examined the effect of exclusion on dead volume measurement. A mobile phase consisting of n-octane, the same chain length as the bonded phase, was employed to ensure no differential interaction between the solute and the two phases. A range of aliphatic hydrocarbons from, n-hexane to n-hexaiiiacohtane were chromatographed at two temperature 30°C and 50°C. The two temperatures were used to ensure that the retention mechanism was solely exclusion and not partition. If partition was the mechanism promoting retention, then different retention volumes... 

---