The Nature of an Aerosol

For a droplet of initial radius rQ, its radius r at lime t may be estimated from equation (1). the various terms of which are listed below. 

D = diffusilivity of the solvent vapour from the sample solution (cm s ) o = surface tension of sample solution (erg-cm ) p = vapour pressure of sample solution (mm Hg X 1-359 = g cm ) 

M = relative molecular mass of the liquid (solvent g mof ) d = density of sample solution (g-tyn ) 

With typical values for water at 20 C, the time taken for a droplet to shrink to 10% of Its original radius may be calculated as an example of the use of equation (1). 

Let the argon sweep flow of the aerosol through a lube of 1 cm radius be 1 L/min. 

If a liquid is vaporized rapidly or its vapor is cooled rapidly, it can form an aerosol consisting of a mixture of purely gaseous components, small droplets, and, sometimes, small particles of solid matter (particulates). Aerosols are dynamic systems, with evaporation from some droplets that become smaller and coalescence of other droplets that grow bigger. Given time and suitable temperatures, the components of aerosols may condense to form a liquid or evaporate to form 

M = relairve molecular mass of the liquid (solvent qmof M  

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