CHEMISTRY · Multi-part · AP · Chemistry · Properties of Substances and Mixtures · Properties of Substances and Mixtures
Problem
Two pure gases, O2 and CO, are each placed in separate, identical 10.0 L rigid containers at an absolute temperature of 298 K and a pressure of 1.00 atm. The molar mass of O2 is 32.00 g mol−1, while the molar mass of CO is 28.01 g mol−1. Assume that each gas behaves ideally.
(a) Identify which gas has the greater root–mean–square (rms) speed at 298 K, and justify your answer without performing a numerical calculation.
(b) The temperature of each sample is increased to 596 K while the volume of the containers remains fixed. Explain qualitatively how the rms speed of each gas changes, and predict whether the percentage increase in rms speed is the same for both gases. Support your reasoning.
(c) Discuss how the differences in rms speed between the two gases at 298 K could influence the relative rates at which they effuse through a tiny pinhole, according to kinetic–molecular theory.