Asample of an unknown volatile liquid was injected into a dumas flask (mflask = 27.0928 g, vflask = 0.1040 l) and heated until no visible traces of the liquid could be found. the flask and its contents were then rapidly cooled and reweighed (mflask+vapor = 27.4593 g). the atmospheric pressure and temperature during the experiment were 0.976 atm and 18.0 °c, respectively. the unknown volatile liquid was

The gas was Hexane

Explanation:

taking the diference between the mass of the flask and the final mass qe can calculate the mass of liquid injected (assuming none escaped the flask):

with the volume of the flask we can get the density of the gas at the indicated pressure and temperature:

From the ideal gases law we have that the density can be calculated as:

Where R is the ideal gases constant = , and M the molecular weight of the fluid. Solving for M:

Note that the temperature is computed in Kelvin T= 18+273=291K

The gas with the closer molar mass is Hexane