28 QUANTITATIVE ASPECTS OF CHEMISTRY
solid salt in the gas stream issuing from the tube. If for any
reason the heating is interrupted during the process, submerge
the jet beneath the liquid, so that water, not air, will be sucked
back into the tube and flask. When about 400 cc. of water have
been forced over, submerge the jet and allow the ignition tube to
cool to room temperature. Raise the beaker to equalize the water
levels, and close the cock. Record the temperature of the lab-
oratory and the barometer reading. Weigh the water in the
beaker on the platform balance, which gives the actual volume of
the oxygen evolved. Calculate its volume under standard con-
ditions. Weigh the tube again, and the loss gives the weight of
oxygen.
Calculation. From your data calculate the weight of 1 liter of
oxygen under standard conditions.
- DETERMINATION OF THE VOLUME OF HYDROGEN DISPLACED
BY ZINC
When hydrochloric acid reacts with zinc a definite volume of
hydrogen is displaced by a given weight of metal. The weight
of zinc dissolved can be accurately determined, and when the
volume of hydrogen liberated is corrected to standard conditions
the ratio between the two is obtained.
Materials: zinc metal, rod 2.5 cm. by 0.6 cm.
hydrochloric acid, 6iV.
Apparatus: 4-inch drying tube and 1-hole rubber stopper.
300-cc. flask.
2.5-inch funnel,
water trough,
iron ring and ring stand,
burette clamp,
wire triangle,
pinch cock.
two 18-inch pieces of rubber tubing,
copper wire.
Data Form:
Weight of zinc before reaction grams
Weight of zinc after reaction grains
Weight of zinc consumed in the reaction grams