Engineers must choose a working gas for an apparatus that will operate at 273 K
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
Engineers must choose a working gas for an apparatus that will operate at 273 K. The apparatus may encounter either 1.0 atm or 10.0 atm of pressure. The table gives measured compressibility factors Z=PV/(nRT) for three candidate gases.
Gas Z at 1.0 atm Z at 10.0 atm
Helium 1.000 1.005
Neon 1.001 1.021
Carbon dioxide 0.997 0.811
(a) Using the data in the table, indicate which gas most closely obeys the ideal-gas law at 1.0 atm and 273 K. Support your answer with quantitative evidence.
(b) For carbon dioxide at 10.0 atm, calculate the percentage deviation of the measured pressure from the pressure predicted by the ideal-gas law at 273 K.
(c) Provide two molecular-level reasons, based on the assumptions of the ideal-gas model, that account for the large deviation of carbon dioxide at 10.0 atm compared with the noble gases.