Friday, September 26, 2014

Classification of Matter "Sandwich"

Watching the Iron and Sulfur reaction.
Classification of matter (COM) is usually the first "real" chemistry topic we tackle in a new year.  This  year I decided to make a "Lab Sandwich" with my classification of matter unit.   I also like to think of this unit as a pyramid, a swimming reference that seems to fit the symmetry of the unit.

To open the unit, I gave my students a mixture of iron, salt, sand, and pebbles to separate.  The lab groups made a flow chart with a detailed plan for obtaining pure samples of each of the four components.  As an extra challenge, I asked them to collect enough data to calculate the mass percent of the parts of the mixture.  I love starting the kids off with an inquiry lab that they really can't mess up.  This particular mixture demonstrates several different physical properties and gives them a chance to learn some basic lab techniques.  This lab is loosely based on Separation of a Mixture found in Flinn ChemTopic Labs:  Volume 1, Introduction to Chemistry.
The pure samples of iron, rocks, salt, and sand (green and brown sand).

Students working through the "Classification of Matter" POGIL
The meat in my COM sandwich is a POGIL that makes the transition from macroscopic observations of matter to the molecular level of matter.  I love this POGIL because the students get an introduction to chemical formulas and a hint of nomenclature along with a particulate perspective on elements, compounds, and mixtures.  This great activity is found in POGIL, Activities for High School Chemistry by Laura Trout.
Sorting the "samples" into elements, compounds, and mixtures.

Watching the iron-sulfur reaction.
The final layer, the icing on the cake you could say, is the famous Iron and Sulfur lab.  The Iron Sulfur Lab This lab is a classic, and we consider it a rite of passage for our chemistry students at Pomfret School.  In this lab, the students study the mixture of iron and sulfur and then they react the mixture to form the compound iron sulfide.  This is also an exciting lab because it's the first time the kids get to use the Bunsen burners.  The comparison of the physical and chemical properties of the new compound and the mixture of the elements is a wonderful culmination to the COM unit.
My labs are all over instagram!

The smell is all part of the experience.

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