Grahams Laws

Graham, Thomas (1805—1869). A Scottish chemist, pioneer in the study of colloids, the diffusion of gases and dialysis. Developed so-called Graham Law which states that velocities of diffusion of any two gases are inversely pro-porrional to the square roots of their densities Ref Hackh s Diet (1944), 386-R... 

GRAHAM LAW. The rates of diffusion of two gases are inversely propurtional to the square roots of their densities. 

The isobaric counter-current diffusion measurements in the modified Wicke-Kallenbach cell employ the validity of the Graham law which states that under isobaric... 

Grahams law also applies to rates of diffusion, which is logical because heavier particles diffuse more slowly than lighter particles at the same temperature. Using Grahams law, you can set up a proportion to compare the diffusion rates for two gases. 

Rearrange Grahams law to solve for Rate Rate A = RateB x... 

SECTION 10.8 It follows from Idnetic-molecular theory that the rate at which a gas undergoes effusion (escapes through a tiny hole) is inversely proportional to the square root of its molar mass (Graham law). The diffusion of one gas through the space occupied by a second gas is another phenomenon related to the speeds at which molecules move. Because molecules undergo frequent collisions with one another, the mean fiee path—the mean distance traveled between collisions- -is short. Collisions between molecules limit the rate at which a gas molecule can diffuse. 

The experiments done by Hoogschagen have the following values 3.03, 2.66 and 2.54 in three runs carried out by him. Thus the Graham law of effusion is experimentally confirmed. Any deviation from this law would point to an additional transport of an adsorbed surface layer. Using two commercial adsorbents with large internal surface area, this effect was detected (Table 7.4-4). 

This is called the Graham law of diffusion, similar in form to the Graham law of effusion eq. (7.4-42) obtained earlier for the free molecular flow (Knudsen flow). 

Substituting the Graham law of diffusion into eq.(8.6-14), we get the final form for the constitutive flux equation for the component 1 ... 

Knowing the flux for the component 1, the flux of the component 2 is calculated from the Graham law of diffusion equation (8.6-16). 

By using the Grahams law equation (8.6-22) into the Stefan-Maxwell equation (8.6-20a), we obtain the following equation expressing the flux in terms of concentration gradient for the component 1 ... 

Graham law The velocity with which a gas will diffuse is inversely proportional to the square root of its density. 

From the net molar diffusion flux density N =N +Ng, flie component diffusion flux densities, and Ng, were determined fix>m the Graham law... 

On the basis of Grahams law, discuss why tennis balls pressurized with air have a shorter shelf-life than those pressurized with sulfur hexafluoride. 

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