Kinetic Energy in relation to the ideal gas law

In summary, the ideal gas law does not include a factor of 3/2 or 5/2 because pressure and energy density are not the same quantity. While they have the same dimensions, they are not equivalent in an ideal gas. Therefore, the ideal gas law factors out the correct quantity, which is energy density multiplied by the total volume.
  • #1
vjk2
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I'm trying to fit this together.

For monotomic molecules, the avg kinetic energy is 3/2 k_b T

for diatomic, it is 5/2 k_b T

PV = n_particles * k_b T

Why is there no factor of 3/2 or 5/2 in the ideal gas law? How is it factored out?
 
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  • #2
A simple answer might be that although pressure and energy density have the same dimensions, they are not the same quantity. For an ideal gas, its pressure and its energy density are not the same. Therefore:

pressure * total volume is not equal to total energy.

energy density * total volume is equal to total energy.
 

1. What is kinetic energy in relation to the ideal gas law?

Kinetic energy is the energy that an object possesses due to its motion. In the context of the ideal gas law, it refers to the energy that gas molecules possess due to their random movement.

2. How does kinetic energy affect the behavior of an ideal gas?

Kinetic energy is directly related to the temperature of a gas. As the temperature increases, the average kinetic energy of the gas molecules also increases, resulting in faster movement and increased pressure.

3. Can kinetic energy be calculated using the ideal gas law?

Yes, the ideal gas law can be used to calculate the kinetic energy of a gas by rearranging the equation to solve for kinetic energy. The formula for kinetic energy is KE = 3/2 * nRT, where n is the number of moles, R is the gas constant, and T is the temperature in Kelvin.

4. How does the ideal gas law explain the relationship between temperature and kinetic energy?

The ideal gas law, PV=nRT, shows that as temperature increases, the pressure and volume of a gas also increase. This is because an increase in temperature leads to an increase in the average kinetic energy of the gas molecules, which results in more frequent and harder collisions with the walls of the container, leading to an increase in pressure.

5. Is kinetic energy the only factor that affects the behavior of an ideal gas?

No, other factors such as volume, pressure, and number of particles also play a role in determining the behavior of an ideal gas. The ideal gas law takes into account all of these factors to describe the relationship between them and the behavior of a gas.

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