Conductometric cell

The parameter can change in a vessel being part of the analytical instrument, for example, an ultraviolet-visible (UV-Vis) spectrophotometric cell [39,41,45,14,47, 48], an infrared (IR) cell [42, 46], or a fluorometer cell [45, 51], or a polarimetric tube [27, 49]. It can change in a reactor vessel where the analytical signal can be read in some way, for example using an optical fiber cell for spectrophotometry [52-54] or a conductometric cell [16,34,40]. Another possibility is to transport the solution from the reaction vessel to the analytical instrument by a peristaltic pump [38]. When altenative ways are not practicable, samples can be taken at suitable time intervals and analyzed apart [29,31,35,39,43,50]. 

The reaction of the same substrate with thiourea in variable-concentration conditions was also followed conductometrically with good results [16]. The reaction was carried out in a thermostatted reaction vessel. An autoburette was used to add a concentrated solution of thiourea. The conductance was read by means of a conductometric cell and acquired by a computer. 

Chemistry Video Consortium, Practical Laboratory Chemistry, Educational Media Film and Video Ltd, Harrow, Essex, UK - Electrochemical techniques (using galvanic cells, using conductometric cells, determining standard electrode potentials, determining solubility products, thermodynamic characteristics of cells, conductometric titrations and using an automatic titrator). 

Conductometry is an electrochemical technique used to determine the quantity of an analyte present in a mixture by measurement of its effect on the electrical conductivity of the mixture. It is the measure of the ability of ions in solution to carry current under the influence of a potential difference. In a conductometric cell, potential is applied between two inert metal electrodes. An alternating potential with a frequency between 100 and 3000 Hz is used to prevent polarization of the electrodes. A decrease in solution resistance results in an increase in conductance and more current is passed between the electrodes. The resulting current flow is also alternating. The current is directly proportional to solution conductance. Conductance is considered the inverse of resistance and may be expressed in units of ohm (siemens). In clinical analysis, conductometry is frequently used for the measurement of the volume fraction of erythrocytes in whole blood (hematocrit) and as the transduction mechanism for some biosensors. 

A plot of log (e — W() versus t gives ak here, P is the ratio of the bridge arms, and a = kr+ArlkT, the value of dt can be made small or even zero by suitable devices. It seems to us an important advantage that c and c need not be identical. This means not only that the solutions need not have exactly the same concentration, but also that the two conductometric cells employed need not be matched. 

As stated in Sect. 21.4, the conductivity of an electrolyte solution is closely related to the conductance and, therefore, the electric resistance measured between the electrodes of a conductometric cell (cross-sectional area A, distance /) when a... 

The surface area of the electrodes and their arrangement in the conductometric cell influence the electric resistance via the quotient l/A, the so-called cell constant. However, these geometric quantities are often difficult to investigate, especially in the case of platinated electrodes. Therefore, the cell constant is determined by using a calibrating solution of known a value (usually a solution of potassium chloride). These days, commercial equipment for measuring conductivity (conductometer) is... 

Mutual differential diffusion coefficients of binary (e.g. [6-8]) and pseudo binary systems (such as, e.g., cobalt chloride in aqueous solutions of sucrose [9]), have been measured using a conductometric cell and an automatic apparatus to follow diffusion. This cell uses an open-ended capillary method and a conductometric technique is used to follow the diffusion process by measuring the resistance of the solution inside the capillaries, at recorded times. Figure 1 shows a schematic representation of the open-ended capillary cell. 

Mutual diEFerential diffusion coefficients of several electrolytes 1 1, 2 2, and 2 1, in different media (considering these systems as binary or pseudo binary systems, depending on the circumstances) have been measured using a conductometric cell [1]. The already published mutual differential diffusion coefficients data are average results of, at least, three independent measurements. The imprecision of such average results is, with few exceptions, lower than 1%. 

The symbols p (ohm m) and k (ohm" m ) denote the specific resisitivity and conductivity, respectively. According to Eq. (31) G depends on the geometric configuration of a conductometric cell, whereas p and k are intrinsic properties of the solution at given external conditions. The ratio of //A is the cell constant which is not determined from physical dimensions but is measured when the cell is filled with one of the standard solutions of a well-defined specific conductivity. Since k reflects not only the characteristics of the solute but also its concentration, it is more practical to define the molar conductance as... 

Fig. 19. Equivalent circuit of a conductometric cell. R is the resistance of interest, Cp ras is a stray capacitance.

MSFIA-GD system for the conductometric determination of ammonium in water samples. Detector homemade stainless steel conductometric cell connected to a conductometer HC holding coil RC reaction coil V solenoid valve. 

The setup is an autoclave 4 (Fig. 8.8) in which two conductometric cells 3 are mounted. One cell contains the solution under study, and another is a reference cell. 

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