An 27 liter indoor air sample is collected in a Tedlar bag in the crawl space of a building built on an old municipal dump. There is a suspicion that methylene chloride vapor may be seeping into the building. The temperature is 32¢K and the pressure is 767.6 millimeters of mercury. The expanded bag is returned to the laboratory for analysis and allowed to equilibrate to 25¢J and 760 millimeters of mercury. One milliliter of the sample is withdrawn from the bag with a gastight syringe. The mass of methylene chloride in the 1 ml aliquot is 28£gg. Calculate the concentration in parts per million by volume (ppm) methylene chloride in the air sample at the time of sampling?
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