Oxidation of Iron - An example of a Combination Reaction Vanderbilt Student Volunteers for Science Training Presentation Spring 2010

Introduction Oxidation: Oxidation usually occurs when an element or compound combines with oxygen. Apples turn brown after they have been cut and left exposed to the air. Iron is oxidizing when it rusts and turns a reddish color This example of rusting is called a combination reaction Rust = iron oxide

Part 1: Rusting of Iron Filings Put cotton ball into a 1oz cup and sprinkle with iron filings. Sprinkle a small scoop of salt Add a squirt of Hydrogen Peroxide Set aside and observe after starting part 2. *the obvious orange color forms within 2 minutes

Part 2: Steel Wool Put steel wool into plastic bag Put plastic bag into cup (line it like a garbage can) Add a spoonful of salt and the rest of the peroxide. Feel the bag and note the temperature (Should be at room temperature) Measure the temperature again in 1 minute Steel wool piece Line like a garbage can

Looking back at Part 1 Look back at the iron filings. Equation: 4Fe + 3O2  2Fe2O3 Before: no rust After: orange color

Return to Part 2. Measure the temperature of the steel wool in the plastic bag now. NOTE: Now at 90 degrees.

Conclusion The reaction in this experiment was a COMBINATION REACTION The temperature of the iron filings plus peroxide plus salt mixture increases, so the reaction is EXOTHERMIC.

Clean Up Wipe thermometers and bring them back. Seal plastic bags and throw away in trash can. If the school does not want you to put it in their trash, put all the bags in a larger bag and bring back to the VSVS lab.