Question

Problem 12.19 a Review Icon The lowest pressure ever obtained in a laboratory setting is 4.0 x 10-11 Pa Part A At this pressure, how many molecules of all would there be in a 20 "Cexperimental chamber with a volume of 0.050 ml? Express your answer as a number of molecules VO AXD ? = molecole

Answer 1

The lowest pressure obtained in the laboratory is
P = 4.0 x 10^-11 Pa
The temperature in the chamber
T = 20⁰C = 293.15 K
Volume of the chamber,
V = 0.050 m³
The ideal gas equation
P V = nRT
Where n is the no. of moles and R is the universal gas constant.
From the relation, we can find the no of moles of air molecules in the chamber.
n = P V / RT
n = 4.0 x 10^-11 Pa x 0.050 m³ / 8.314 (J/Mol.K) x 293.15 K
n = 8.206 x 10^-5 moles.
The number of air molecules is
N = 8.206 x 10^-5 moles x 6.023 x 10²³ mol^-1
N = 4.942 x 10¹⁹ molecules