17 Nov 2007

What happens when chemical compounds are added to water?

In-Class Activity

Submitted by Barbara Reisner, James Madison University
Course Level: 
Topics Covered: 

It’s very surprising how little students remember from general chemistry.  This assignment helps students make connections between the macroscopic properties of solutions and what happens at the molecular level.  This activity serves as a bridge between sections on acid-base chemistry and coordination chemistry.

Students are solicited for their models of the behavior of different chemical compounds in water in class and asked to put these models on the board.  We then look at the properties of these solutions (color, acid-base) and refine these models in class.

Students are then shown what happens when NaOH(aq) is added to NiCl2(aq) and asked to provide a molecular-level model.  Again, they put their models on the board and we discuss their models.

 I figure out what students have learned by asking a nearly identical question on an hour exam, the final, or both.

Equipment needs: 

50-mL Ehrlenmeyer flasks
graduated cylinder
pH meter

Creative Commons License: 
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