1. Add strands of aluminum metal to 16 x 150
mm test tube. If any strands are longer than 1-1/2",
bend them in half.
2. Moisten the hole in the #0 rubber stopper
and also one end of the glass right angle bend.
Carefully insert the right angle bend into the
stopper. Attach the rubber tube to the other end
of the glass bend. Set the stopper assembly aside
for now.
3. Put on your safety goggles and gloves. Add
just enough 1.0N hydrochloric acid, HCI, to the
test tube to cover the aluminum metal, not over
1-1/2".
Note: The aluminum metal has an oxide coating
on its surface. This coating acts as a barrier
between the metal and the acid, and it prevents
the reaction from proceeding at its maximum rate.
4. While holding the test tube at a 45 degree
angle, gently warm the acid solution, do not boil
(a candle could be used as the heat source). The
warm acid will gradually remove the oxide coating
and the rate of reaction between the aluminum
and the acid will increase.
5. Insert the stopper assembly into the test
tube. Use the 400 ml beaker to support the test
tube.
6. Fill the 100 ml beaker with water. Place the
free end of the rubber tube in the beaker.
7. Observe the rate at which bubbles of hydrogen
gas are escaping from the end of the rubber tube.
8. As soon as the rate slows down to the point
where it is possible to count each bubble as it
rises to the surface, begin taking data. While
one person keeps track of time, another counts
bubbles released.
Count the number of bubbles released in 30 seconds.
Repeat this process, counting the number of bubbles
released in 30 second intervals, for a total of
at least eight, 30 second time segments, or until
the number of bubbles released during a 30 second
interval has dropped to about 4. Record all data.
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