Lighting Student Interest In Science

Chemists Have Solutions

Solids, liquids, and gases dissolve to form solutions.  In chemistry class, students made a concentrated solution of calcium acetate in water. By mixing together this concentrated calcium acetate solution with ethyl alcohol, students form a colloidal gel that acts like the commercial product Sterno®.  The formation of the gel is a physical phenomenon and not a chemical reaction. When this gel is burned, it can be used as a heat source more desirable than pure alcohol because it is less likely to spill.

2 C2H5OH + 7 O2 -> 4 CO2 + 6 H2O

Students roasted their homemade marshmallows over the sterno. The homemade marshmallows roasted differently than store-bought ones, giving a creamier and smoother melted interior.

The exact structure of the gel is not known, but the calcium acetate solution probably traps the alcohol inside a flexible lattice. If the gel were to sit for several days, the alcohol and water would evaporate, leaving behind the solid calcium acetate.

The video that follows was assembled a few years ago.  A newer video was created this week, but was overly large for this post. I have tried to reduce the size but it has not been going well.

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