Electrolytes kinematic viscosity

For a rotating-disc electrode with a radius r = 1 cm in an aqueous electrolyte (kinematic viscosity of water 0.01 cm s at 20 °C) the critical rotation rate is 10,000 rot min. ... 

Conductivity of electrolyte Kinematic viscosity Metal ion diffusivity... 

A hypothetical rotating-disk ceU is shown below for electrowinning copper cations from a solntion containing Co = 65 g/l at 40°C and 101 kPa. Assume that the diffusivity and the electrolyte kinematic viscosity are 10 cm js and 0.60 cm j3, respectively. Each disk has a radius of 50 cm, a width of 6 cm, and only a 160° segment is immersed in the electrolyte. Assume a cell current efficiency range of 0.50 < e < 1. 

The kinematic viscosity of MEM containing aqueous electrolytes at different concentrations of MEM and ZnBr2 and at different temperatures has been studied [68] (see Table 8). 

Kinematic viscosities of aqueous electrolyte phases containing Et4N+Br and Bu4N + Br and various concentrations of ZnBr2 were studied by Cedzynska [77]. Ionic conductivity of bromine storing phases was estimated [56] by applying the... 

Table 8. Kinematic viscosity (m2sH ) of aqueous electrolyte containing MEM and 3 mol L l ZnBr2 (taken from Ref. [68])...

Viscosities and specific weights of complexes and the corresponding aqueous phases, with the aim of simulating realistic battery conditions with MEP MEM ratio of 1 1, 3 1 and 6 1 in the electrolyte at 50, 75 and 100% states of charge, were studied in a temperature range between 10 and 50 °C [83], Kinematic viscosities between 5 10 6 and 30 -10 6 m2s of the complex phases were found. MEP-rich ones. 

Flow of the liquid past the electrode is found in electrochemical cells where a liquid electrolyte is agitated with a stirrer or by pumping. The character of liquid flow near a solid wall depends on the flow velocity v, on the characteristic length L of the solid, and on the kinematic viscosity (which is the ratio of the usual rheological viscosity q and the liquid s density p). A convenient criterion is the dimensionless parameter Re = vLN, called the Reynolds number. The flow is laminar when this number is smaller than some critical value (which is about 10 for rough surfaces and about 10 for smooth surfaces) in this case the liquid moves in the form of layers parallel to the surface. At high Reynolds numbers (high flow velocities) the motion becomes turbulent and eddies develop at random in the flow. We shall only be concerned with laminar flow of the liquid. 

Ferrocene is dissolved in propylene carbonate solution (together with a suitable supporting electrolyte). The solution has a kinematic viscosity of u = 0.239 cm s and the diffusion coefficient of ferrocene is 3 x 10 cm s T Calculate the thickness of the diffusion layer at a frequency of 30 Hz. 

The kinematic viscosity is the ratio of the electrolyte coefficient of viscosity and its density. 

However, using this technique for measuring the diffusion coefficient requires an accurate knowledge of the electrode area A, the bulk concentration cx of the diffusing species, the number n of electrons transferred in the reaction, and the kinematic viscosity v of the electrolyte. Errors in measuring these quantities can cause a substantial error in determining D. 

Reynolds number (characteristic solution velocity x characteristic length/kinematic viscosity) faradaic resistance for an electrochemical reaction electrolyte resistance between a reference electrode and a working electrode Schmidt number (= v/D)... 

These equations repeat those previously set down. Flete, u is the kinematic viscosity, and a is the thermal diffusivity. The subscripts have been dropped in the convective diffusion equation, and D can be the binary diffusion coefficient, the effective electrolytic diffusion coefficient, or the diffusion coefficient of the fth species. The molar concentration is to be interpreted in the same context. In the energy equation, sometimes referred to as the heat conduction equation in the form written, heat flux due to interdiffusion and due to viscous dissipation have been neglected as small. Heat sources are also absent. 

For a clearer observation of the effect of electrolyte concentration on the viscosity. Figure 1.8 shows the plots of kinetic viscosity vs electrolyte concentration for several typical electrolytes. It can be seen that with increasing electrolyte concentration, the kinematic viscosity of the corresponding solution also increase steadily. 

For the usage of electrochemical rotating electrode technique. Table 1.8 lists the data of kinematic viscosity at several typical electrolyte solutions as a function of temperature. 

Table 1.8. Kinematic Viscosity at Several Typical Electrolyte Solutions as a Function of Temperature...

From Figure 1.10, it can he seen that the plots of kinematic viscosity vs pressure at temperatures below 308 K have a minimum at 0—1973 atm, and the calculation indicated that the activation energy of viscous flow has a minimum at about 1973 atm. These decreases in viscosity and activation energy with increasing pressure on the low-pressure side of the minima were ascribed to a break of the bulky water structure like hydrogen-bonded tetra-hedra. However, when the pressure is increased to a value of higher than 2000 atm, a monotonic increase with further increasing pressure can be observed. The similar trend was observed not only for pure liquid water but also for several electrolyte solutions. ... 

Utilizing concentrated electrolyte solutions is an intuitive method to increase ionic conductivity and amount of active material present in the system. This approach certainly raises operating efficiencies and improves the kinetic parameters of electrode activity, as expected [6]. There is a concurrent drawback, however, that increasing the amount of electrochemically active species present in the electrolyte might negatively influence diffusion parameters due to the resultant increase in kinematic viscosities of the solution [37, 38]. As is the case of the zinc half-cell, the kinetics and behavior of the Br2/Br redox reaction in the bromine half-cell are also influenced by the presence and concentrations of supporting electrolytes in solution [39]. 

In this equation, the term Ap = Ip - Pbl corresponds to the difference, in absolute value, of the volumetric mass of the electrolyte between the interface (p ) and the bulk (Pb), L is a characteristic length (in this case the height of the electrode) and v represents the kinematic viscosity. For a binary electrolyte of concentration Cb, we find ... 

In ECM, the main electrolytes used are aqueous solutions of (i) sodium chloride, and (ii) nitrate, and occasionally (iii) acid electrolytes. These solutions would have a typical concentration and density of 400 g/1, and 1100 kg/m respectively the electrolyte will have a kinematic viscosity of about 1 mm /s. The solution would normally be operated at temperatures between about 18 C and 40°C. Temperatures above ambient are often preferred because the electrolyte solution warms during ECM due to electrical heating caused by the passage of current. The machining action is often found to be easier to control if the electrolyte is maintained at a higher temperature from the outset. This is usually achieved by heating the electrolyte in its... 

Technical data electrode width = 0.1m electrolyte gap = 0.03 m density of electrolyte = 10 kg/m Schmidt number = 1300 kinematic viscosity = 10 mVs sphere diameter = 0.002m sphere density =1800 kg/m voidage of loosely packed spheres = 0.42. 

Here, i is the measured current density, 4 is the kinetic current density, io is the diffusion limited current density, n is the number of electrons transferred per oxygen molecule, F is the Faraday constant (96485 C moF ), D is the diffusion coefficient of the molecular O2, Co is the concentration of molecular O2 in the electrolyte, v is the kinematic viscosity of electrolyte, and co is the angular rotation rate (rad s ). Plotting versus. yields n from the slope and 4 from the intercept on the 4 axis. The f obtained from the Koutecky-Levich plot can also be utilized to obtain the Tafel plot, logf versus E, to determine the Tafel slope and exchange current density (io). 

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