A fixed amount of argon is confined in a rigid container at 300 K
CHEMISTRY · Single correct · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A fixed amount of argon is confined in a rigid container at 300 K. The pressure calculated from PV=nRT is 5.0 atm, but the measured pressure is 7.0 atm. Which statement most plausibly accounts for the higher measured pressure?
(a) Attractive forces between argon atoms increase the effective impact force, producing the higher pressure.
(b) After the gas was sealed it warmed above 300\,K, so the actual temperature is higher than the one used in PV=nRT, giving a larger pressure.
(c) The finite volume occupied by the argon atoms reduces the free volume, so PV/nRT underestimates the pressure.
(d) At this pressure some argon atoms form transient dimers, effectively increasing n and thus the pressure above the ideal‐gas value.