A 5.0 L steel cylinder contains 2.0 mol of CO and an identical cylinder contains 2.0…
CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
A 5.0 L steel cylinder contains 2.0 mol of CO2 and an identical cylinder contains 2.0 mol of CH4. Both cylinders are held at 250 K, a temperature well below the normal boiling point of either gas, and the external pressure is adjusted so that the measured pressure in each cylinder equals the pressure predicted by the ideal–gas law at 298 K.
Use the information above to analyze how each gas will deviate from ideal behavior once the temperature is lowered to 250 K while the volume and amount of gas remain fixed.
(a) Identify whether intermolecular attractions or finite molecular volume will be the dominant cause of non-ideal behavior for CO2 and for CH4 under the stated conditions. Justify your answer by referencing molecular properties.
(b) For each gas, predict qualitatively (greater than, equal to, or less than 1) the value of its compressibility factor Z=nRTPV at 250 K and 5.0 L. Provide a brief explanation.
(c) Explain, at the particulate level, why one of the two gases is expected to show the larger percent deviation from ideal pressure at 250 K.