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Difficulty: EasyKinetic Theory of Matter and Pressure of Gases

According to the kinetic theory of matter, what causes the pressure exerted by a gas on the walls of its container?

  1. The continuous elastic collisions of gas molecules with the walls of the containerAnswer
  2. B
    The attractive forces pulling gas molecules towards the container walls
  3. C
    The heat capacity of individual gas molecules transferring thermal mass to the walls
  4. D
    The static expansion of fixed gas molecules taking up space

Answer

The pressure exerted by a gas is due to the continuous elastic collisions of gas molecules with the container walls.
According to the kinetic theory of gases, gas particles are in rapid, random motion. When these particles collide elastically with the walls of the container, they undergo a change in momentum. The average rate of momentum change per unit area exerted by countless particle impacts manifests as macroscopic gas pressure.

Step-by-Step Solution

1
Identify the basic postulate of the kinetic theory of gases regarding particle motion.
Gas molecules are in rapid, constant, and random motion.
Kinetic theory models gas behavior based on particle movement.
2
Relate particle motion to force and pressure on the container boundary.
When particles hit the container wall, they undergo a change in momentum, imparting a force on the wall.
Force is defined as the rate of change of momentum (F=ΔpΔtF = \frac{\Delta p}{\Delta t}).
3
Define pressure in terms of force per unit surface area.
The total force exerted per unit surface area by continuous collisions results in gas pressure (P=FAP = \frac{F}{A}).
Pressure is force distributed over a given surface area.

Key Concept

Kinetic Theory of Matter and Pressure of Gases
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Kinetic Theory of Matter and Pressure of Gases

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