Ramsay radon

The rightmost column of the periodic table, that of the noble gases, was put there largely through the efforts of William Ramsay. He had a part in the discovery of argon, the identification of helium on earth[1], the proposal that argon and helium belonged in a new column of the periodic table, and the discovery of krypton, neon, and xenon to fill that column. Ramsay even had a hand in establishing the atomic weight of the noble gas radon, the subject of this exercise.

Ramsay and Robert Whytlaw Gray built a balance sensitive to half of a millionth of a milligram. They reported the data shown below on the density of the "emanation of radium," as the gas was then known. Volumes are in units of thousandths of a cubic millimeter, and they refer to conditions of 0°C and 1 atm. Masses are in units of millionths of a milligram.

samplevolumemass
I72.8722
II58.5564
III58.5577
IV67.7658
V73.0706
Use the ideal gas law to compute the molar mass of each sample and report the mean and standard deviation of the molar mass. (Hint: remember that a liter is defined as a decimeter cubed.)

Reference

William Ramsay & Robert Whytlaw Gray, "Density of the emanation of radium," Comptes Rendus 151, 126-8 (1910).
[1]It had previously been known only in the sun, from its spectrum.
Copyright 2003 by Carmen Giunta. Permission is granted to reproduce for non-commercial educational purposes.

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