Halothane, molecular weight

As an illustration, consider the determination of the molecular weight of halothane, an inhalation anesthetic. The density of halothane vapor at 71°C (344 K) and 768 mmHg (1.01 atm) is 7.05 g/L. To obtain the molecular weight, you calculate the moles of vapor in a given volume. The molar mass equals mass divided by the moles in the same volume. From the density, you see that one liter of vapor has a mass of 7.05 g. The moles in this volume are obtained from the ideal gas law. 

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