I Why does the Dry Air Gas Constant vary?

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The discussion centers on the varying values of the dry air gas constant, which range from 286.9 to 287.22, depending on the source. Participants highlight that differences in these values may arise from measurement methods, the date of data collection, and the molecular weight of dry air. While some argue for the need for exactness, others suggest that variations are insignificant and that three significant figures are generally sufficient for practical calculations. The conversation concludes with the acknowledgment that while precision is important, minor discrepancies should not hinder overall calculations. Ultimately, the dry air gas constant can be considered accurate enough for most applications despite its variations.
Robert James Liguori
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I'm confused on why the dry air gas constant varies:
Can someone please explain why it differs and how it is constructed. Thanks, Robert

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to within 3 significant figures these are all the same !
It would be worth checking how each source obtained the value, especially the date when the values were measured.
Methods vary and improve over the years
 
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I am not a physicist... so you are implying that the differences in the values is insignificant? To me, it should be exact... or a means should be in place to get the exact value at each given location of sampling... if this was indeed possible, which it may not be. Please advise.
 
universal gas constant = 8314.32 (in 1976 Standard Atmosphere)
molecular weight of dry air = 28.964

8.3143 / 28.964 = 0.28705634580859 (e.g., 287.056)
 
I figured it out... thanks for your help.

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Can you measure the length of your kitchen table exactly? Why not? Are you going to let that keep you from buying a tablecloth?

Even if the value of the gas constant is not exact, does that bring your calculations to a screeching halt (until you find the exact value, which doesn't exist)? Isn't 3 significant figures accurate enough for you?
 
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On these words of wisdom, the OP's question has been answered. Thread closed.
 

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