1. A standard rotary pump can produce a “vacuum”

1.  A standard rotary pump can produce a “vacuum” pressure of 10^-3 torr. Assuming that only nitrogen is present what is the single-particle collision frequency and mean free path at T = 298 K. How many particles will collide with a surface of an area of 1 cm² in one second?

1. 2. A cryogenic pump can produce a “vacuum” pressure of 10^-10 torr. What is the single-particle collision frequency and mean free path at T = 298 K. How many particles will collide with a surface of an area of 1 cm² in one second?
2. 3. a) The diffusion coefficient for Xe at 273 K and 1.00 atm is 0.5 × 10^-5 m²/s. What is the collisional cross-section of Xe?

b) The diffusion coefficient for N₂ is three times greater than that of Xe under the conditions above. What is the collisional cross-section of N₂?

1. 4. One of the proposed methods for storing hydrogen for vehicles powered by fuel cells is to store it in solid palladium. One of the limiting factors is the rate of diffusion of the gas through the metal. To estimate this, the diffusion of hydrogen gas through a 0.005 cm thick piece of palladium foil with a cross-sectional area of 0.750 cm² is measured. On one side of the foil, a volume of gas maintained at 298K and 1 atm is applied, while a vacuum is maintained on the other side. After 24 hours the volume of hydrogen has decreased by 15.2 cm³. What is the diffusion coefficient of hydrogen gas in palladium?