Two monatomic gases, helium and neon, are mixed in a sealed container and brought into thermal equilibrium at temperature T . If the molar mass of helium is 4.0 g/mol and the molar mass of neon is 20.2 g/mol , then _______.
A. all the atoms have the same average speed
B. the average speed of the neon atoms is greater than the average speed of the helium atoms
C. the average speed of the helium atoms is greater than the average speed of the neon atoms
D. the atoms diffuse from high temperature to low temperature
E. all the atoms have exactly the same velocity.
Answer:
A. all the atoms have the same average speed
Explanation:
The entropy of the two monatomic gases (helium and neon) depends on temperature of the sealed container. Increase in temperature of the container increases the speed of the atoms while decrease in temperature of the container decreases the speed of the atoms. Also at constant temperature, all the gaseous atoms will move at a constant speed (that is randomly or no direction).
Since, the sealed container was brought into thermal equilibrium, meaning that the temperature of the system is constant. Thus, all the atoms have the same average speed.