Beads -> Balanced Chemical Equations

April 27, 2011 at 11:15 AM

C + O2 -> CO2, right? No problem.

Collecting gas from a burning coal:

Using bromothymol blue to see if the collected gas is carbon dioxide.

And we are always safety-conscious:

But some students didn’t realize that the atoms themselves re-arrange and are the SAME atoms that just change their bonds from one side to the other side of the equation and IN REAL LIFE too, that chemical reactions conserve matter. They can slide by with memorizing and learning the ‘turn-the-crank way to balance equations well enough to do okay on the state tests (in OMG 2 weeks…). But they really needed time to think about what was going on at the atomic and molecular level. So glad I cancelled the lab and took this slowly.

It’s kind of fun too, using white boards and markers, working together and ooh, bright, clinky counters. I had no idea that $7 of vase stones from the craft shop would be my best learning tool all year.

The conservation of matter, of atoms, in a chemical reaction is a profound law of the universe – it’s why they are stardust, how we are all connected with the earth and sky, and why we all contain bits of carbon that were once part of Einstein, or Marilyn Monroe. The carbon emphasis on the lab sheet: 3. Investigate chemical reactions stochiometry makes the connection to the Problems with Oil and the Great Carbon Race that has woven through this year’s curriculum and through 7th grade life science too. It’s a really nice realization, an ah ha moment with a little fizz of awe and wonder at the universe.

After letting them have some time to think through the methane + O2 reaction, I had students share their thinking.

And finally, shock, horror…

They did the chapter in the text to consolidate what they were learning.


Entry filed under: Chemistry topics, Curiosity, The Problems with Oil Project. Tags: , , , .

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