Question

1) According to kinetic-molecular theory, what makes a substance a gas? 2) What are the two primary assumptions about the atoms or molecules of a gas made by the ideal gas law? Under what conditions are these assumptions most valid? 3) Describe why a gas exerts pressure on a molecular scale.

Answer 1

1. Answer

According to the kinetic theory of gases are the substances that consist of particles that are so small so that the volume occupied by them is negligible relative to the total volume of the container.

2. Answer

According to kinetic molecular theory two main assumptions are-

1. It must consist of molecules or atoms with constant motion colliding with each other and with the walls of the container. The collisions are perfectly elastic.
2. The particles are so small that the total volume occupied by the gas molecules is negligible compared to the total volume of the container. The attraction or repulsion among the gas particles are negligible.

These assumptions are valid only at very high temperature and low pressure.

3. Answer

According to the kinetic molecular theory, the gas molecules continuously undergo elastic collision with each other and with the walls of the container. Thus a force will be exerted on the walls of the container. The pressure of the gas is the sum of all the forces produced by the collisions. That is why the gas exerts pressure on a molecular scale.