**SUMMER
RESEARCH PROGRAM FOR SCIENCE TEACHERS**

**Jackie
Watt-Daniels**

**Marta Valle
Model HS, Manhattan**

**LAB
LESSON**

**How can we accurately make different
solutions of different concentrations?**

__Materials:__

__Chemicals__

Sodium Chloride(NaCl) Balance Stirring Rods

Calcium Chloride(CaCl2) Beaker(250ml) Spatulas(3 per group)

Magnesium Sulfate(MgSO4) Periodic Table Weighing Paper

Deionized Water [Teaching Standard D- Make accessible science materials]

__Procedure:__

1) Students will separate into groups. Each group should contain no more than three students.

2) Students should obtain all the necessary equipment needed.

3) Select one substance from above and begin to calculate using the molarity formula the weight necessary to make the following concentrations of solutions: .25M, .5M and .75M.

4) Stir the required amount of substance into the required volume.

5) Repeat step #3 for each of the two remaining substances.

__Conclusion:__

Each group will be required to post their results on the board. After the results are posted, each group will compare their answers and if there is any disagreement each group will discuss possible reasons for the difference. [Teaching Standard B- Orchestrate scientific discourse]

__Questions:__

1) How could incorrect calculations, using the molarity formula affect your results?

2) Why is it necessary to be accurate when performing chemical experiments?