Kinetic Molecular Theory Gas Laws - Oakland Schools

Procedure:
1. On your table should be a pair of gloves for each student participating in the lab,
tray, a straw, a beaker, and a fine-point permanent marker. One student should
½ fill the beaker with water, and one student should bring the tray over to the
fume hood to obtain a pair of cotton swabs. For your first trial, use the swab
with the green dot (ammonia) and the swab with the red dot (hydrochloric acid).
Note that each swab has a wet end and a dry end marked with a particular color
of dot. Use the tray to transport the cotton swabs back to your lab table.
2. Using a fine point permanent marker, mark the straw at the points approximately
2 cm from the ends. These marks represent the starting points from which the
gases will diffuse. Measure and record the total distance between these two
marks.
3. While one person holds the straw steady, another person should simultaneously
insert the two swaps in opposite ends of the straw. The swabs should penetrate
to the points you previously marked.
4. Watch for the formation of a white aerosol ring inside the tube. Mark this point
with the sharpie. The ring consists of tiny crystals of ammonium chloride (NH 4 Cl).
Measure and record the distance traveled by the HCl gas from its initial mark to
the point where the ring forms. Do the same for the NH 3 gas.
5. Remove the cotton swabs and immediately place them beaker of water your
prepared in step 1. This precaution will minimize the escape of HCl and NH 3 gas
into the laboratory. It will also dilute the concentrated solutions and allow them
to neutralize each other.
6. Repeat steps 1-5 using a different straw and using cottons swabs with
hydrochloric acid (red dot) and sodium hydroxide (yellow dot).
7. Dispose of materials as directed by the teacher. Wash hands with soap and
water.
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