Question

This question relates to Graham's Law of Effusion & to Chapter 9 in The Principles of Modern Chemistry Ed.8

[The question is below this is what I am having trouble on: I found the rate of effusion to be 6.7952 molecules/sec, the average speed to be 469.6 m/s, but I am having most trouble with finding the number density in order to then find A in the equation Zw=(1/4)(N/V)(avg. speed)(A) to finally find the radius for the answer to (a). As for b, I am having trouble understanding the concept of enrichment factor to appropriately answer the question asked.]

3. A spherical bulb with a volume of 500 cm 3 is evacuated to a negligibly small residual gas pressure and then closed off. One hour later, the pressure in the vessel is found to be 2.00 × 10 -7 atm because the bulb has a tiny hole in it. Assume that the surroundings are at atmospheric pressure, T = 300 K, and the average molar mass of molecules in the atmosphere is 28.8 g/mol.

a. Please calculate the radius of the hole in the vessel wall, assuming it to be circular.

b. Assume that the surroundings contain only N2 (take its molar mass as 28.0 g/mol) and O2 (take its molar mass as 32.0 g/mol), and the mole fraction ratio between the two species is X(N2 ):X(O2 ) = 4:1. When the pressure in the vessel is found to be 1.00 × 10 -7 atm, the mole fraction ratio X(N2 ):X(O2 ) inside the vessel should be higher, equal to, or smaller than 4:1? Please explain your answer by calculating the enrichment factor for N2.

Answer 1