Science/Strand IV/Content Standard 2/High School/Benchmark 1
Benchmark Question: How does matter change?
Focus Question: How does matter change in chemical
After the teacher
demonstrates, describes, and models a chemical change, students will
perform a chemical change in small lab groups. The groups will model the
chemical change using colored mini marshmallows and toothpicks. The
following is a suggestion of an appropriate chemical change investigation
The Rusting of Iron
- Rinse a small marble-sized
sample of steel wool (Fe) in a dish of dilute HCl (0.1M).
- Place the sample in the
bottom of a test tube and invert the test tube. The steel wool should
fit snugly enough into the tube so that it doesn’t fall out.
- Fill a small beaker
(approx. 250 ml) with water to a depth of about two cm.
- Place the inverted test tube
into the beaker with the water.
- Let this stand for an hour
- Observe the water level and
the steel wool. The water level in the tube should rise as a result of
oxygen (O2) leaving the gaseous state and combining with
iron (Fe) and forming the solid rust (Fe2O3).
- Discuss the following
reaction that occurs:
4Fe + 3O2 2Fe2O3
- Groups should use one color
of marshmallow for iron, another for oxygen, and construct a model
with toothpicks (for bonds) to represent the reaction.
Small groups will describe
the chemical change in writing and will share this writing with other
groups and classes.