Assume that you are on an expedition in outer space. You are the
only chemist on
board the spacecraft, and so you must make critical (and accurate)
decisions or you
will endanger the life of the crew (including yourself!) What
follows are two typical
problems you might encounter during your voyage. Always fill in
the blank (if there is one) with your answer. If space (no pun
intended) is given for calculations, you must show all
calculations.
Your first stop is on the planet Flaskon. The captain of the ship,
Earl N. Meyer, named the planet himself. Before leaving earth,
he had filled a 1000 liter tank with oxygen gas, at a temperature
of 25 degrees Celsius and a pressure of 10.0 atm. The oxygen was
to be used as a defensive weapon in the event that your landing
was not appreciated by the Flaskonites. (Oxygen gas
is lethal to the inhabitants of Flaskon - they normally breathe
nitrous oxide, N2O, or laughing gas.)
But the atmospheric pressure
on Flaskon is 5.4 atm, and the temperature now (at midday) is
-100 degrees Celsius. Your captain wants to know if the oxygen
tank will discharge in case of an emergency. You tell him that
it __________ discharge, because the pressure in the tank is ____________.
You explain, of course, that the pressure in the tank must be
greater than the atmospheric pressure for the gas to be discharged,
and you show these calculations to support the conclusion you
made above:
After several hours, the captain has noticed several Flaskonites
passing by the ship. They seem disinterested, and he concludes
that either they are not hostile or they are extremely stupid.
Suddenly the safety officer on ship, Ethyl Acetate, announces
that the oxygen generator has malfunctioned. Shortly the oxygen
in the ship will be gone. Your captain wants to know if the partial
pressure of the oxygen needed for survival (0.20 atm) can be attained
by releasing all of the oxygen gas from the tank into the cabin,
which has a volume of 1.10 x 105 liters and a temperature
of 298 Kelvin. He can add an inert gas (like neon) to make the
total pressure in the cabin 1 atmosphere. If so, he will put all
of the oxygen from the tank into the cabin; if not, he must use
a backup oxygen source which is in very limited supply. You tell
him that the tank ____________ be sufficient to produce 0.20 atm
partial pressure of oxygen, and tell him that the partial pressure
of the oxygen (from the tank) in the cabin, if all the oxygen
is released from the tank, would be ___________. You show the
following calculations to support your conclusions:
Congratulations! Your mission is complete. Hopefully, so is your solution to this problem of the week.