Question

A technician is testing vacuum pumps. The pumps are connected to a vacuum chamber with a volume of 1.40 m3, allowed to run for a set period of time, and the temperature and pressured measured. For a particular pump, the final chamber temperature and pressure are respectively measured to be 325 K and 5.00 × 10-10 Torr (where 1 Torr = 133 Pa). Determine the number of molecules in the chamber at the end of the pumping time. You may treat the contents of the vacuum chamber as an ideal gas. molecules Need Help? Readt ,-/5 points SerPSE 10 20. 1.0P 005 My Notes Ask Your Teacher For a cylinder of hydrogen (H2) gas, you have been informed that the rms speed of the molecules is 640 m/s. Determine the temperature of the gas in degrees K. Use 2.0159 x 10-3 kg as the mass of a mole of hydrogen molecules.

Answer 1

Pressure P = 5 times 10^- 10 Torr = 6.65 times 10^- 8 pa volume v = 1.4 m^3 Temperature T = 325k R = 8.314 J Vertical-bar mol Ik By using PV = nRT n = PV/RT = 6.65 times 10^- 8 pa times 1.4m^3 /8.314 J mdlk times 325 k n = 3.45 times 10^- 11 no. of molecules = n times 6.022 times 10^23 = 3.45 times 10^- 11 times 6.022 times 10^23 = 2.078 times 10^13 molecules