Learning Exercise

Instructor Information:

1. Instructor prepares a demonstration of how chemical reactions are very
similar to massing an object.

2. Use a balance to introduce the concept of what happens when one object is
placed on a platform on one side of the balance and another of less mass is
placed on the other platform on the other side. In order for the objects to be
balanced, an equality between the two must exist.

3. In chemistry, this idea is satisfied by the Law of Conservation of Matter.
Loosely interpreted; matter can be neither created nor destroyed, only
re-distributed.

4. When the precise amount of material(mass) is represented on both sides, then
the imbalance is neutralized and the objects become balanced.

5. Place an unbalanced equation on the board. Once the students have completed
their activity with the pinto beans, balance the equation and demonstrate using
atomic mass units that the total quanities of mass units on both sides of the
equation are the same.

Students

1.Students will experiment with massing different quantities of pre-measured
portion cups filled with pinto beans. They will attempt to balance the
pre-measured amounts by adding or subtracting pinto beans until the balance has
been equalized.

2. They will discover that by using basic mathematic techniques, they should be
able to calculate the amount of beans required to equalize the imbalances on the
scale.

3. Next, the students will complete the worksheet for practicing balancing
equations and turn it in to the instructor.

4. The students will be given time to practice the timed activity to increase
their speed.