This is one of my favorite demos with students. Students get to hold methane bubbles in their hand and then experience the exothermic reaction when it reacts with oxygen in the air. The look on their faces is pure amazement.
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Energy is needed to start a chemical reaction. Unsurprisingly this is called activation energy. The video above shows the activation needed to make red phosphorus react with oxygen in the air.
A former brilliant student of mine, Hayden Parker, informed me that the head of safety matches are not made of red phosphorus. Science Theatre at Michigan State University explains.
A "striking surface" is made of sand, powdered glass, and a chemical called "red phosphorus". The head of a safety match is made of sulfur, glass powder, and an oxidizing agent.
This is why safety matches cannot be lit on any surface. The striking surface contains the red phosphorus and not the match itself.
I recently presented at the CSTA Conference and I was able to pick up a few new demonstrations. In the past it was really difficult to demonstrate or do a lab activity that involved the electrolysis of water. Luckily I sat in on Tara Krisch's (Orange Grove Middle School) presentation on compounds. She shared a simple way for students to do water electrolysis. The second demo also shows electrolysis, but in a slightly more colorful way.
Thirty ml of sugar (sucrose) (C12H22O11) is mixed with 30 ml of sulfuric acid (H2SO4). A chemical reaction takes place to produce carbon, water (H2O) and sulfur trioxide (SO3). It's a fun chemical reaction to observe because there are dramatic changes in color, smell (make sure good ventilation is present), and temperature (so much heat is released that it melts the plastic cup). Gases are also produced which add to the drama.