Thursday, February 20, 2020

Apologia Chemistry: Solubility and Module 11

Today the Chem class redid the Solubility Rules Lab.  I was concerned about cross contamination.  I do teach before, during, and after labs.  For example, we reviewed solubility before resuming lab.  I also asked the kids to identify the types of chemical reactions are involved in precipitate reactions. (Double replacement reactions.)  Before lab, I asked them to identify the solubility rules they already understood.  For example, nitrate compounds are soluble.  Period.  Sodium and potassium compounds are soluble.  Period.  Most silver and lead compounds are insoluble---EXCEPT silver nitrate, silver acetate, lead nitrate, and lead acetate.

During lab, I usually just prompt them and answer questions. For example, the silver nitrate and lithium chloride did not produce a precipitate.  I had the kids add powdered lithium chloride to the silver nitrate to observe the precipitate.   After lab, we summarized their findings.  What are the Solubility Rules?  I make a point of emphasizing that the rules are based on lab observations--just like their lab observations.










After lab the class did reaction predictions for these precipitate reactions--double replacement reactions.  I reviewed the symbols for precipitate reactions.  We did one more set of reaction predictions and identified the solid precipitates.  I also went over the solubility rules lab rubric.

Solubility Rules Lab
Title: Solubility Rules Lab Report


Background:  What does solubility mean?  What is a precipitate? Define soluble and insoluble.  Use the Apologia Chemistry textbook.


Materials: List all of the materials, such as disposable transfer pipettes or wood stir sticks.  The students may summarize the reactants. For example, over one dozen different soluble compounds may be included in the materials instead of listing each compound, such as sodium phosphate solution.


Procedures: The procedures are summarized.  The various reactants, such as barium chloride and potassium sulfate are combined in reaction plates.  The student observes each reaction to note precipitates.


Data Chart:  The data tables my be hand-drawn or electronic versions.


Reaction: Predict, write, and balance one of the precipitate reactions observed during lab.  


Discussion: Identify sources of error.

Citation or Attribution: Use MLA formating to cite the textbook.




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