Chap Posted January 24, 2012 Share Posted January 24, 2012 (edited) 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 January 24, 2012 by Chap Link to comment Share on other sites More sharing options...
hypervalent_iodine Posted January 24, 2012 Share Posted January 24, 2012 Perhaps I'm missing something here, but the ideal gas equation I've always seen is written as PV=nRT. Link to comment Share on other sites More sharing options...
Chap Posted January 24, 2012 Author Share Posted January 24, 2012 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? Link to comment Share on other sites More sharing options...
DrRocket Posted January 24, 2012 Share Posted January 24, 2012 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. 1 Link to comment Share on other sites More sharing options...
Chap Posted January 24, 2012 Author Share Posted January 24, 2012 Thanks. However M should stand for "molar mass" right? Not "relative molecular mass", in the second equation? Link to comment Share on other sites More sharing options...
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