pV = nRT = mRT/Mso
M = mRT/(pV) .1) Dumas investigated mercury, finding that at 446°C and 765 torr, 0.812 g of mercury vapor filled a vessel of volume 0.235186 L. From these data, compute the molar mass of mercury.
2) Dumas reported results on a compound he called "liquor of Libavius." He carried out the experiment at 124°C, but he expressed the vapor density for standard conditions of 0°C and 1.00 atm. If this compound remained a vapor at 0°C and 1.00 atm, its density would be 11.9514 g/L.
a) What is the molar mass of "liquor of Libavius?"
b) "Liquor of Libavius" is a compound of tin and chlorine. Look at a modern periodic table and suggest a formula consistent with the molar mass.
3) The raw data that Dumas collected included temperature, pressure, and mass measurements. He measured the mass of a vessel when it was filled with air, when it was filled with the vapor he was investigating, and when it was filled with (liquid) water. For a certain compound of arsenic and chlorine, the data, all at 758 torr, were:
mass of vessel filled with dry air at 25°C = 97.432 ga) Find the molar mass of this arsenic chloride. First, assume that the volume of the vessel in mL is the same as the mass of the water that fills the vessel. (The mass of the air that fills the vessel is negligible here.) The mass of the vapor is the difference between the mass of vessel filled with vapor and that of the empty vessel. (The mass of the air that fills the vessel is not negligible here.) Find the mass of the empty vessel from the reported mass of the vessel filled with air and the density of air at 25°C and 758 torr, which is 1.187 g/L.
mass of vessel filled with vapor at 175°C = 99.420 g
mass of vessel filled with water at 23°C = 638.740 g
4) Dumas reported results for sulfur that made him (and others) question the reliability of his method. "In the first experiment to which I submitted this element, I had no doubt that some error had escaped my attention," he wrote. However, he kept getting similar results. The average of several trials, carried out in different vessels and at different temperatures, was 8.49 g/L (converted to standard conditions of 0°C and 1.00 atm).
a) What is the molar mass of sulfur, according to his data?
b) Look at a modern periodic table; what does it suggest for the formula of sulfur vapor?
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