Question

The gas hydrogen is diffusing through a sheet of vulcanized rubber 20 mm thick at 25 ∘C. The partial pressure of H_2 inside is 1.5 atm and 0 outside. Using the data from table 6.5−1, calculate the following.

a. The diffusivity D_AB from the permeability PM and solubility S and compare with the value in Table 6.5-1.
b. The flux N_A of H at steady-state.

Answer 1

To find the diffusivity D_AB, use the equation D_AB = PM / S with values from Table 6.5-1. The flux N_A can be calculated with Fick's first law using the diffusivity and Henry's Law to determine gas concentrations.

Step-by-step explanation:

To calculate the diffusivity DAB from the given permeability PM and solubility S, you would use the relationship DAB = PM / S. However, the permeability and solubility values are not provided in the question, so they need to be obtained from Table 6.5-1, which is referenced in the question. Once DAB is calculated, it can be compared with the value given in the table.

The flux NA of hydrogen at steady state can be calculated using Fick's first law of diffusion: NA = -DAB (C1 - C2) / ΔX, where C1 and C2 are the concentrations at the high-pressure and low-pressure sides respectively, and ΔX is the thickness of the material the gas is diffusing through. To find C1 and C2, you can use Henry's Law, which relates the solubility of a gas in a liquid to its partial pressure: C = K * P, where K is Henry's Law constant and P is the partial pressure of the gas.