Vapor pressure curve solid particles

Tungsten powder is gray to black, depending on particle size the solid exhibits a light gray, lustrous surface. M.p. 3650°C, b.p. > 5000°C (calculated from the vapor pressure curve) d 19.3. Hardness 4.5-8, depending on the history. Crystal structure A 2 type. 

The fluid phase that fills the voids between particles can be multiphase, such as oil-and-water or water-and-air. Molecules at the interface between the two fluids experience asymmetric time-average van der Waals forces. This results in a curved interface that tends to decrease in surface area of the interface. The pressure difference between the two fluids A/j = v, — 11,2 depends on the curvature of the interface characterized by radii r and r-2, and the surface tension, If (Table 2). In fluid-air interfaces, the vapor pressure is affected by the curvature of the air-water interface as expressed in Kelvin s equation. Curvature affects solubility in liquid-liquid interfaces. Unique force equilibrium conditions also develop near the tripartite point where the interface between the two fluids approaches the solid surface of a particle. The resulting contact angle 0 captures this interaction. 

Capillary cohesion phenomenon — Kelvin equation. The theory of capillary cohesion and Kelvin equation are the theoretical basis of physical vapor adsorption. When the steam of adsorbate contacts with porous solid surface, it will form liquid film of the adsorbate on the surface adsorption field. The films in the pore bend variously with the pore diameter, while the films in the outer surface of particles are relatively flat. The film thickness of liquid of adsorption increases with increase in vapor pressure. When it reaches a certain moment, the gravity between the curved liquid surfaces sufficiently liquidity the vapor from gaseous automatically, and completely fill the pores. This phenomenon is known as capillary cohesion. 

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