IDENTIFICATION OF GASES
In this experiment, you will prepare three gases, carbon dioxide, oxygen, and hydrogen. After using the
splint test to distinguish the gases from each other, you will test the gas you observed yesterday and try to
identify it. Record your observations in a suitable table at each step.
Procedure
Goggles are required at all times in the laboratory. Most of the materials you need are at each lab
station. The solutions are in dispensers on the lab tables. Read instructions and labels carefully!
Control: the splint test in air. Hold an empty test tube at a 45° angle. Ignite a wooden splint from the
candle, shake out the flame, and hold the glowing splint at the mouth of the empty tube to observe the
behavior of the splint in air.
Carbon dioxide gas. Dispense 5 mL of 3M hydrochloric acid (diluted from 12M HCl Stock Solution)
solution into a test tube. Begin the generation of carbon dioxide gas by adding 2 marble chips (white
rocks). Let it bubble for a few moments to push out air and fill the tube with gas, then ignite a wooden
splint from the candle, shake out the flame, and hold the glowing splint at the mouth of the reaction tube,
held at 45° as before. Record your observations.
Oxygen gas. Dispense 5 mL of 6% hydrogen peroxide (diluted from 30% stock solution) another test
tube. Begin the generation of oxygen gas by adding several crystals of potassium iodide catalyst (white
crystals). Let it bubble for a few moments to push out air and fill the tube with gas, then test the gas with
the splint test as above. Record your observations.
Hydrogen gas. Dispense 5 mL of 3M hydrochloric acid solution into another test tube. Begin generation
of hydrogen gas by adding 2 chunks of mossy zinc metal (gray irregular metal chunks). Let it bubble for
a few moments to push out air and fill the tube with gas, then test the gas with the splint test. Record your
observations.
Identification of the unknown gas. Dispense 5 mL of blue solution into another test tube. Add a pellet of
aluminum metal (smooth gray pellet). Let it bubble for a few moments to push out air and fill the tube
with gas, then test the gas with the splint test. Record your observations. Compare the behavior of this
gas to the behaviors of carbon dioxide, oxygen, and hydrogen, and identify the unknown gas.
When you have finished, discard the reaction mixtures in the waste beaker and used splints in the trash.
Rinse the test tubes thoroughly and leave them inverted on a paper towel. Replace used materials (splints
and solids in the dish). Leave your lab station neat and materials ready for the next lab team.
IDENTIFICATION OF GASES
Purpose:
To prepare, collect, and test three gases; to identify an unknown gas.
Procedure:
Each gas is prepared by mixing the ingredients shown in a large test tube.
The gas is tested by holding a glowing splint at the mouth of the tube.
gas
air
preparation
none (control)
carbon dioxide
hydrochloric acid
+
marble chips
hydrogen peroxide
+
potassium iodide
hydrochloric acid
+
zinc metal
blue solution
+
aluminum
oxygen
hydrogen
unknown gas
results of splint test
Conclusion:
IDENTIFICATION OF GASES
Purpose:
To prepare, collect, and test three gases; to identify an unknown gas.
Procedure:
Each gas is prepared by mixing the ingredients shown in a large test tube.
The gas is tested by holding a glowing splint at the mouth of the tube.
gas
air
preparation
none (control)
carbon dioxide
hydrochloric acid
+
marble chips
hydrogen peroxide
+
potassium iodide
hydrochloric acid
+
zinc metal
blue solution
+
aluminum
oxygen
hydrogen
unknown gas
Conclusion:
results of splint test