NOTES AND PROBLEMS 45
Vst = volume of gas under standard conditions.
Vobs = the observed volume under conditions of experiment.
t = temperature of the gas.
p = pressure upon the moist gas.
aq. tens. = tension of saturated aqueous vapor at f (see table).
PROBLEMS
- Reduce 125.3 cc. of gas at 725 mm. to 760 mm. pressure.
- A cylinder of 2500-cc. capacity contains oxygen under
91.5 atmospheres pressure. Find volume in liters after the
gas is run into a tank under atmospheric pressure.
- Reduce 125.3 cc. of gas at 25.8° to 0°.
- A sealed glass tube contains 125.3 cc. of gas at 27°
and 783 mm. pressure. What will be the pressure if the
tube is heated to 300° without change of volume?
- Reduce 125.3 cc. of gas at 740 mm. and 20.7° to stand-
ard conditions.
- Reduce 125.3 cc. of gas at 15.3 atmospheres and
— 65.5° to standard conditions.
- Reduce 125.3 cc. of gas measured over water at 740
mm. and 20.7° to standard conditions.
- A certain quantity of dry hydrogen gas occupies 2,275
liters at 25° and 760 mm. If this gas were bubbled through
water and collected in a vessel over water, what volume would it
then occupy at the same temperature and the same barometric
pressure? Assume that no hydrogen is dissolved in the water.
Gay-Lussac's Law of Combining Volumes. The measurement
of the volumes of gases which enter into chemical reaction led
Gay-Lussac to perceive the existence of an extremely simple
relationship which is known by the above title and which may be
stated as follows: The volumes of gases which react chemically
are in the ratio of small whole numbers. Furthermore, if the
products of the reaction are also gaseous their volumes are also in
the relation of small whole numbers to each other and to the vol-
umes of the original gases.
Gay-Lussac was unable to explain this law on the ground of
any reasonable hypothesis. He tried to postulate that equal
volumes of different gases must contain the same number of
atoms, but this postulate was almost at once found to be un-
tenable and he had nothing better to offer.
