Question

State True or False.

In the microscopic model of the gas, all the molecules are supposed to move with the same velocities.

• A. True
• B. False

Answer 1

The correct option is B False

Microscopic model of an ideal gas:

The model shows that the pressure that a gas exerts on the walls of its container is a consequence of the collisions of the gas molecules with the walls.

• The number of molecules is large, and the average separation between molecules is great compared with their dimensions. This means that the volume of the molecules is negligible when compared with the volume of the container.
• The molecules obey Newtons laws of motion, but as a whole they move randomly. By randomly we mean that any molecule can move in any direction with equal probability. We also assume that the distribution of speeds does not change in time, despite the collisions between molecules. That is, at any given moment, a certain percentage of molecules move at high speeds, a certain percentage move at low speeds, and a certain percentage move at speeds intermediate between high and low.
• The molecules undergo elastic collisions with each other and with the walls of the container. Thus, in the collisions, both kinetic energy and momentum are constant.
• The forces between molecules are negligible except during a collision. The forces between molecules are short-range, so the molecules interact with each other only during collisions.
• The gas under consideration is a pure substance. That is, all of its molecules are identical.