1.  You are working in a lab and need to anesthetize a small rat.  You plan to put the rat in a closed plastic container and inject an amount of liquid sevoflurane to produce an induction concentration of 4%.  If the container has a volume of 2 liters, how much sevoflurane should you inject?

Answer:   0.5 ml

The density (weight per ml) of sevoflurane is approximately 1.5.

Therefore, each ml of sevoflurane weighs 1.5 grams.

The molecular weight of sevoflurane is 200.

Therefore each ml contains 1.5 (grams/ml) 200 (grams/mole)  = 0.0075 moles.

Each mole of an ideal gas produces 22.4 liter of vapor (gas).  Remember PV =nRT (p = pressure, V = volume, n = number of moles, R = the ideal gas constant, T = absolute temperature).

Therefore 0,0075 moles is the equivalent of 0.168 liters or 168 ml of vapor per liquid ml of sevoflurane.

If we want a concentration of 4% in the container that would be 0.04 X 2 liters or 0.08 liters (80 ml).

Since each ml of liquid sevoflurane produces 168 ml of vapor, then the amount that needs to be injected into the container is roughly 0.5 ml.

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