How Does the Structure of N2 Affect Its Kinetic Energy Calculation?

[DanAbnormal]

Just a quickie.

For example, the total kinetic energy of N molecules is

= (3/2)NkT = (3/2)nRT

If a question were to ask you to find the such energy for a sample of N[tex]_{2}[/tex] would it make the equation

(5/2)kT?

Does the subscript 2 make it diatomic, and hence have two molecules, I am not sure, it could cost me marks though.

 

[Astronuc]

If N is the number of molecules, is N² just a very large number, N-squared.

See this - http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/kintem.html#c1


If E is the average energy per molecule, then the total energy would be NE for N molecules. If one replaces N with N², what is the result?

 

[DanAbnormal]

If N is the number of molecules, is N² just a very large number, N-squared.

See this - http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/kintem.html#c1


If E is the average energy per molecule, then the total energy would be NE for N molecules. If one replaces N with N², what is the result?

Sorry, "N" isn't the number of molecules. Its supposed to be N subscript 2, as in "N" for Nitrogen.
Does the subscript 2 make the N from the equation = 2?

 

[Renge Ishyo]

Does the subscript 2 make it diatomic, and hence have two molecules

N2 is one molecule composed of two nitrogen atoms connected by a triple bond. You wouldn't have to modify your original equation to do the calculation as far as I can see.

 

[Ygggdrasil]

N₂ is one molecule that consists of two atoms. The average translational kinetic energy of any gas will be (3/2)Nk_BT.

You may be confusing the average kinetic energy with the heat capacity as the molar heat capacity (C_v). C_v for a diatomic gas is (5/2)k_BT, whereas C_v for a monatomic gas is (3/2)k_BT. The difference comes because diatomic molecule have rotational modes of motion which can absorb energy whereas monatomic atoms do not. However, the rotation of diatomic molecules does not affect their translational kinetic energy.