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In many applications of diffusiophoresis, the motion is driven by gradients in the concentration of a salt (electrolyte) concentration, [2] [3] such as sodium chloride in water. Colloidal particles in water are typically charged, and there is an electrostatic potential, called a zeta potential at their surface.
The dilute gas viscosity contribution to the total viscosity of a fluid will only be important when predicting the viscosity of vapors at low pressures or the viscosity of dense fluids at high temperatures. The viscosity model for dilute gas, that is shown above, is widely used throughout the industry and applied science communities.
Depending on the solute and range of concentration, an aqueous electrolyte solution can have either a larger or smaller viscosity compared with pure water at the same temperature and pressure. For instance, a 20% saline ( sodium chloride ) solution has viscosity over 1.5 times that of pure water, whereas a 20% potassium iodide solution has ...
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
Consequently, if a liquid has dynamic viscosity of n centiPoise, and its density is not too different from that of water, then its kinematic viscosity is around n centiStokes. For gas, the dynamic viscosity is usually in the range of 10 to 20 microPascal-seconds, or 0.01 to 0.02 centiPoise. The density is usually on the order of 0.5 to 5 kg/m^3.
The school experiment uses glycerine or golden syrup as the fluid, and the technique is used industrially to check the viscosity of fluids used in processes. Several school experiments often involve varying the temperature and/or concentration of the substances used in order to demonstrate the effects this has on the viscosity.
The thermophoretic force has a number of practical applications. The basis for applications is that, because different particle types move differently under the force of the temperature gradient, the particle types can be separated by that force after they have been mixed together, or prevented from mixing if they are already separated.
Intrinsic viscosity [] is a measure of a solute's contribution to the viscosity of a solution.If is the viscosity in the absence of the solute, is (dynamic or kinematic) viscosity of the solution and is the volume fraction of the solute in the solution, then intrinsic viscosity is defined as the dimensionless number [] = It should not be confused with inherent viscosity, which is the ratio of ...