Two separate samples of an ideal monatomic gas are confined in equal-volume rigid…
PHYSICS · Multi-part · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics
Problem
Two separate samples of an ideal monatomic gas are confined in equal-volume rigid containers by a removable partition. The left-hand sample is at TL=400K and the right-hand sample is at TR=200K. At time t=0 the partition is suddenly removed, allowing the gases to mix while the combined container remains thermally insulated from the environment.
(a) Describe, in terms of intermolecular collisions, how energy is redistributed among molecules from the two initial samples during the first few milliseconds after the partition is removed.
(b) Explain qualitatively how the overall distribution of molecular speeds for the combined gas evolves from the instant just after removal of the partition until thermal equilibrium is reached.
(c) Identify the macroscopic quantity whose constancy signifies that the system has reached thermal equilibrium, and relate this macroscopic condition to the microscopic picture you described in part (b).