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Ideal gas problem?

Chap
in Homework Help

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I know the ideal gas equation (and how to derive it):PV= (1/3) x N x m x (U)^2 where: P-Pressure, V-Volume, N- number of molecules, m- mass, U- mean speed of molecules. The problem is my book gives a "different" version of the equation:PV= (1/3) x n x M x (U)^2 where: P-Pressure, V-Volume, n- number of moles, M- relative molecular mass, U- mean speed of molecules It goes on explain that: the relative molecular mass (M) of any substance expressed in grams contains the Avogadro constant number of molecules.

That is: M = m x (Avogadro constant).

Is this equation (and explanation) correct? I can't find a website which gives a suitable explanation. Can anyone please give me a link or any useful information?Thanks.

Edited by Chap

  • Author

Perhaps I'm missing something here, but the ideal gas equation I've always seen is written as PV=nRT.

 

yes, you're right, PV=nRT is the ideal gas equation., but that equation I gave is used in deriving the ideal gas equation, is it not?

 

is that it? Am I looking in the wrong direction?

I know the ideal gas equation (and how to derive it):PV= (1/3) x N x m x (U)^2 where: P-Pressure, V-Volume, N- number of molecules, m- mass, U- mean speed of molecules. The problem is my book gives a "different" version of the equation:PV= (1/3) x n x M x (U)^2 where: P-Pressure, V-Volume, n- number of moles, M- relative molecular mass, U- mean speed of molecules It goes on explain that: the relative molecular mass (M) of any substance expressed in grams contains the Avogadro constant number of molecules.

That is: M = m x (Avogadro constant).

Is this equation (and explanation) correct? I can't find a website which gives a suitable explanation. Can anyone please give me a link or any useful information?Thanks.

 

Your two equations are equivalent. They are also equivalent to PV=nRT.

  • Author

Thanks. However M should stand for "molar mass" right? Not "relative molecular mass", in the second equation?

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