Estimate the Diffusivity of Hydrogen

Example 5.7 Estimation of Diffusivity of Hydrogen and Oxygen in Water Vapor Estimate the diffusivity of hydrogen in water vapor and oxygen in water vapor at 1 atm and 307 K and compare with experimental data in Table 5.4. 

Example 5.1-2 Comparing two estimates of gas diffusion Use the Chapman-Enskog theory and the empirical correlation in Equation 5.1-9 to estimate the diffusion of hydrogen in nitrogen at 21 °C and 2 atmospheres. The experimental value is 0.38 cm /sec. Solution For the Chapman-Enskog theory, the key parameters are... 

Estimate the diffusivity of carbon monoxide through a gas mixture of ethylene, hydrogen, and nitrogen with the known mole fractions given in the following table. The mixture is at 295 K and 2 atm. 

Estimate the value of if the liquid described in Prob. 10-11 contains catalyst particles of 100 mesh size. Suppose that the agitation caused by the gas bubbles increases only slightly above the minimum value ( c)grav- The density of the particles is 1.8 g/cm and the diffusivity of hydrogen in the liquid is 6 x 10 cm /sec. 

As the working temperature of the substrate was increased, the induction period (the delay time) of increased conductivity decreased due to increased rate of lateral diffusion of hydrogen atoms towards the sensor. The activation energy for surface migration of particles along a Si02 substrate estimated from the tilt of the Arrhenius plot was found to be about 20 kj/mol. 

Figure 9. Qualitative potential energy diagram for the diffusion of a hydrogen along the principal C3 axis of the [Nii2(CO)2iH]3" trianion, as estimated from closest Ni-H contacts...

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