Everyone has Problems, but Chemists have Solutions

Kathy Kreidler Thornridge High School
15000 Cottage Grove Ave.
Dolton, IL 60419
(708) 841-5180 X 2585


The student will
1. relate chemical solutions to everyday solutions.
2. define molarity.
3. explain how solutions of different molarities are prepared.

Materials needed:

Teacher demonstration:

2 packets drink mix table salt, NaCl
2 quart pitcher balance
2 drinking glasses--different sizes beakers--different sizes
labelled reagent bottles of stuffed cloth mole models* differing molarities one-liter volumetric flask Strategy:

1. Have labelled reagent bottles sitting out on the desk.
2. Following student directions, prepare a pitcher of drink mix, bringing out
the terms solvent, solute, solution and homogeneous.
3. Pour some of the prepared drink into two different-sized glasses. Ask the
students to compare the concentration of solution in each of the three
containers. All concentrations are 1 pack/pitcher.
4. Ask how a 0.5 pack/pitcher could be made. Students should realize that the
packet must be opened and the amount desired must be weighed out on the
5. Point out the reagent bottles and explain that terms such as 0.5M and 3M are
expressions of solution concentration.
6. Using a 1 liter volumetric flask, demonstrate how to make a 0.1M solution of
sodium chloride, drawing parallels to making a pitcher of the drink mix.
7. Pour some of the 0.1M NaCl into different-sized beakers. Ask the students to
compare the concentration of solution in each of the containers.
8. To recap, bring out a 1 liter beaker and several stuffed moles. Adding one
mole gives a 1 Molar solution. Stuffing in a second mole gives a 2 Molar
solution. With a flourish, separate a third mole at the velcro strip
joining the front and back ends and make a 2.5 Molar solution.
9. The lesson can be extended by placing stuffed moles in other sizes of
beakers and calculating the molarity of the resulting "solutions."


*Weird Science #5 (for mole pattern). Make one special mole by constructing
the front and back halves separately and then joining them with a velcro strip.
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