A tubular fluorescent lamp in a fully evacuated supply compartment on the international space station was originally filled with a small amount of mercury vapour. When the lamp began to flicker the astronauts complained there was a tiny hole in the tube. They measured that the pressure inside the tube dropped from 2.31torr to 2.09torr after 24 hours. The volume of the tube is 1.39L. The temperature was at a constant of 82K over the 24h period. Please calculate the diameter of the hole in millimeters (assume it is round).

Please help...after several attempts I still can't get the right answer.

First I got the moles using the first pressure, and the second mole using the second pressure. Then I subtracted the two to get the final mole. To get the number of molecules I did avogadro's number multiplied with the moles. I then used the Z wall formula. Please help step by step! thanks!