Sax and Lewis12 describe the hazards of breathing air containing appreciable amounts of an asphyxiant (a gas that has no specific toxicity but, when inhaled, excludes oxygen from the lungs). When the mole percent of the asphyxiant in the air reaches 50% marked symptoms of distress appear and at 75% death occurs in a matter of minutes. A small storage room whose dimensions are 2 m x 1.5 m x 3 m contains a number of expensive and dangerous chemicals. To prevent unauthorized entry, the room door is always locked and can be opened with a key from either side. A cylinder of liquid carbon dioxide is stored in the room. The valve on the cylinder is faulty and some of the contents have escaped over the weekend. The room temperature is 25°C.

(a) If the concentration of CO2 reaches the lethal 75 mole% level, what would be the mole percent of O2?

(b) How much CO2 (kg) is present in the room when the lethal concentration is reached? Why would more than that amount have to escape from the cylinder for this concentration to be reached?

(c) Describe a set of events that could result in a fatality in the given situation. Suggest at least two measures that would reduce the hazards associated with storage of this seemingly harmless substance.