Day 62 – Keeping warm is just a phase away. #modchem #chemchat #180blog

So in my first year of teaching, I remember try to teach my students about saving oranges from the frost. Many farmers will dowse their trees in water the night before a freeze. Then as the water freezes, it releases heat both into the oranges and the air. Thus something freezing releases energy. This relationship between thermal energy and phase changes is counter intuitive for many people an a tough misconception to crack.

The energy bar chart is helping my students crack this barrier. To give them an example of this, I boiled water and put it into two beakers. One had four test tubes filled with lauric acid (mp ~43C) and the other was just water. I then used the labquest to track the temp of both waters and the Laurie acid.

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I then let it sit and we watched:

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So as we watched we saw the temperature drop faster for the water with the test tube, but then it stayed warmer longer. This was not a perfect system, but it showed energy flowing from thermal to phase and back. Also it help the students continue to break the stranglehold that water has on their perception of phase changes.
There was also a great exchange by my #chemchat buddies rlthat inspired me to set this up.

“@CentralScience: @dragan39 @stardiverr @cookp http://t.co/NHbUM0rUBp or done this http://t.co/pEtbfxCtbo. @ThomsonScience @KristinGregory7″

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