Chapter 13.1, Problem 17SSC

To determine

To Compare: The number of particles in a $2.0-L$ sample of carbon dioxide gas and the number of particles in a $2.0-L$ sample of helium gas if both samples are at the same temperature and pressure.

Answer to Problem 17SSC

There are an equal number of particles in the two samples.

Explanation of Solution

Introduction:Force is an interaction between two or more than two objects, that causes a pull or push action between those objects. A force (per unit area) that acts on any object is defined by pressure.

The force exercised by gas can be explained by employing the "kinetic-molecular theory" of gases. In this theory, gases are made up of very small particles, the same particles that make up liquids and solids. But particles are now generally separated and have random motion (in constant) at very high speed, and also, they make elastic collisions with each other. When gas particles touch a surface, they rebound without dissipating kinetic energy. So, the forces exerted by these collisions result in gas pressure on the surface. There is zero loss of energy from these collisions. This is the main relation between gas particles and pressure.

There are an equal number of particles in the two samples. Ideal gas molecules do not repel or attract each other. In an ideal gas, the size of particles is not relevant to the volume of the gas or the pressure exerted by the gas.

Conclusion:

In two samples, there are an equal number of particles.