Standard 2/Middle School/Benchmark 1
Benchmark Question: How does matter undergo physical
Focus Question: What physical changes take place
when butane is heated and cooled?
Materials: 1 can butane lighter fluid, thirty
locking sandwich bags, dry ice cut in small sections.
Each student will zip a
small locking sandwich bag almost closed and leave an opening just large
enough to insert the nozzle of a butane can. The teacher will squirt a
small amount of butane (about one-quarter teaspoon) into the bag and
quickly seal it. The body heat of the students’ hands and fingers will
cause the butane to boil and become a gas that inflates the bag. Students
will discuss why the bag inflates (the volume of the gas increases, because
the molecules move farther apart). Students may rub their bags over a small
block of dry ice to reduce the heat energy in the bag. Students will
discuss why the bag deflates (the volume of the gas decreases, because the
molecules move closer together).
Students will draw a picture
of the molecular motion for each change of state the butane undergoes.
This experiment can be
repeated as often as desired and the changes of evaporation and
condensation discussed. Sublimation of the dry ice can also be discussed.
- Students should be aware of the dangers of
butane gas (do not inhale, flammable).
- Students should dispose of butane gas
- Room should be well ventilated during
activity involving butane gas.
- Do not reuse bag for other activities.
- Do not handle dry ice with bare hands.
Note: Due to the porous property of the
locking sandwich bags, bags cannot be prepared in advance.