Deriving pV=NkT from N=Na*n and k=R/Na

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In summary, the gas constant is ##R=k_B N_a##. To find pV, you need to find the relation between n and R, and then use that to find pV.
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Hannah7h
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I've attempted to use N=Na*n -where N is that total number of particles of a gas, Na is the Avogadro constant and n is moles. And then attempted to use k=R/Na -where k is the Boltzmann constant and R is the molar gas constant. I got as far as N/n=R/k but then not sure how to get from this to the final equation- if this is even the right way
 
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  • #2
You cannot get the ideal gas law by just manipulating the definition of Avogadro number and its relationship with other constants.
Whereas the definition of Avogadro number's is very general, the ideal gas law is valid only for ideal gases. So you need to start with a model of ideal gas and find a relationship between pressure and other parameters.
For example,try to find how the pressure depends on the concentration of particles and their average speed.
You can find the this done in introductory books on kinetic-molecular theory of gases.
 
  • #3
Hannah7h said:
I've attempted to use N=Na*n -where N is that total number of particles of a gas, Na is the Avogadro constant and n is moles. And then attempted to use k=R/Na -where k is the Boltzmann constant and R is the molar gas constant. I got as far as N/n=R/k but then not sure how to get from this to the final equation- if this is even the right way

Are you trying to convert pV=nRT to pV=NkT?

It would help you are clear on what you want to do, especially on your starting point.

Zz.
 
  • #4
ZapperZ said:
Are you trying to convert pV=nRT to pV=NkT?

It would help you are clear on what you want to do, especially on your starting point.

Zz.

Ah yeah sorry, it wasn't clear, basically I wanted to know what you would derive pV=nRT from and then how you would derive it from those equations, but also it would be good if you could tell me how to get from pV=nRT to pV=NkT
 
  • #5
The gas constant is just ##R=k_B N_a##.
 
  • #6
I think I know what you are looking for.
First, you make a few assumptions :

  • The gas is made up of discrete molecules
  • These molecules don't interact with one another
  • The gas molecules collide elastically with the walls of the container
  • The gas molecules occupy no relevant Volume
  • The gas molecules move equally in all three dimensions
I am just going to stop here because I remembered a video on this:

The derivation starts at 9 minutes
 
  • #7
Tazerfish said:
I think I know what you are looking for.
First, you make a few assumptions :

  • The gas is made up of discrete molecules
  • These molecules don't interact with one another
  • The gas molecules collide elastically with the walls of the container
  • The gas molecules occupy no relevant Volume
  • The gas molecules move equally in all three dimensions
I am just going to stop here because I remembered a video on this:

The derivation starts at 9 minutes


Ohhh ok, I see how its done now, thank you
 
  • #8
Glad I could help

Tazerfish :biggrin:
 
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FAQ: Deriving pV=NkT from N=Na*n and k=R/Na

What is the significance of the equation "pV=NkT"?

The equation "pV=NkT" is known as the ideal gas law, which relates the pressure (p), volume (V), and temperature (T) of an ideal gas. It also includes the number of moles (N) and the Boltzmann constant (k) as important factors.

How is the ideal gas law derived from the equation "N=Na*n"?

The equation "N=Na*n" represents the number of molecules (N) in a gas, where Na is Avogadro's constant and n is the number of moles. By substituting this into the ideal gas law, we can derive the equation "pV=NkT."

What is the relationship between the Boltzmann constant and Avogadro's constant?

The Boltzmann constant (k) is equal to the gas constant (R) divided by Avogadro's constant (Na). This means that the Boltzmann constant is a proportionality constant that relates the average kinetic energy of particles in a gas to its temperature.

Can the ideal gas law be used to describe real gases?

The ideal gas law is an approximation that works well for most gases at low pressures and high temperatures. However, it may not accurately describe the behavior of real gases under extreme conditions, such as high pressures or low temperatures.

How does the ideal gas law relate to the kinetic molecular theory?

The ideal gas law is based on the kinetic molecular theory, which states that gas particles are in constant motion and have negligible volume compared to the container they are in. The ideal gas law mathematically describes the relationship between the pressure, volume, and temperature of a gas as predicted by the kinetic molecular theory.

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