The Thermite Reaction in slow motion!

The Thermite Reaction in slow motion!  See molten iron fall from the reaction vessel (flower pot)! An initial reaction of sucrose (C12H22O11) + potassium chlorate (KNO3) + a couple drops of sulfuric acid (H2SO4) is used to initiate the more violent thermite reaction in which the reactants, iron III oxide (Fe2O3) + aluminum (Al), produce iron (Fe) and aluminum oxide (Al2O3). 

The person in the hold my IPAD is Mike Sirowich (The Physics Teacher at Seymour High School) who was busy recording the demonstration with his new thermal imagining camera (Video 2).

Video 1 - Slow Motion

Video 2 - Recorded with the Thermal Imager

Thermite vs. a Hamburger

The thermite reaction releases 852 kilojoules (kJ) of energy whereas a hamburger typically has only 600 Calories (Big Mac has ~600 Calories).  Looks like thermite wins!  Good  news for summer grilling.  Either way I am having a burger tonight!

However, a calorie is defined as the amount of energy need to raise the temperature of 1 gram of water 1 degree Celsius.  In the food business, for some reason, they use Calories, notice the capital 'C', therefore 1 Calorie = 1 kilocalories = 1000 calories.  Are we in the clear yet since it is 852 kJ vs. 600  Calories?  Not really as 1 calorie = 4.2 Joules or 1 Cal = 4.2 kJ which means the 600 Cal must by multiplied by 4.2 in order to convert this to kJ.  When we do this the the 600 Cal is equivalent to 2520 kJ.

The thermite reaction is shown below.  It is a reaction between powdered aluminum and iron powdered iron III oxide (rust).  To get the reaction to occur it must be heated to around 2200 degrees Celsius which is why an ignition reaction must first be used.  I used a mixture of potassium chlorate and sucrose plus a few drops of sulfuric acid.

Video 1) Thermite Ignitor (KClO3 + Sucrose + Sulfuric Acid)

Video 2) Thermite

The good thing about having the AP Chem Test first is it leaves more time at the end of the year to perform neat demos.