Should diatomic gas be regarded as ideal gas?

[kelvin490]

We know that one model for ideal gas is monoatomic gas with no attractive force between atoms, elastic collision and some other assumptions. I would like to ask if there exist a gas behave exactly the same but the only difference is it's a diatomic gas (or more complicated structure), should it be regarded as an ideal gas? (Note that the average KE for monoatomic and diatomic gas are different)

 

[Chestermiller]

We know that one model for ideal gas is monoatomic gas with no attractive force between atoms, elastic collision and some other assumptions. I would like to ask if there exist a gas behave exactly the same but the only difference is it's a diatomic gas (or more complicated structure), should it be regarded as an ideal gas? (Note that the average KE for monoatomic and diatomic gas are different)

Yes. We can treat diatomic gases as ideal gases also, if the pressure is low enough. The only difference is in their heat capacity.

Chet

 

[kelvin490]

Yes. We can treat diatomic gases as ideal gases also, if the pressure is low enough. The only difference is in their heat capacity.

Chet

Thanks for the answer. For monoatomic ideal gas the cv is 3R/2 and cp is 5R/2, so γ=5/3 is for monoatomic ideal gas only?

 

[Chestermiller]

Thanks for the answer. For monoatomic ideal gas the cv is 3R/2 and cp is 5R/2, so γ=5/3 is for monoatomic ideal gas only?

Yes.