Experiment No. 3: Electrochemistry and Corrosion
Date Performed: November 4, 2010
Electrochemistry is a branch of chemistry that studies chemical reactions which take place in a solution at the interface of an electron conductor and an ionic conductor and which involve electron transfer between the electrode and the electrolyte or species in solution. Basically, an oxidation-reduction reaction (redox reaction) is a reaction in which electrons are transferred between species or in which atoms change oxidation numbers. Oxidation is the portion of the redox reaction in which there is a loss of electrons by a species or an increase in the oxidation number of an atom. Reduction is the part of a reaction in which there is a gain of electrons by a species or a decrease in the oxidation number of an atom. Something that is oxidized loses electrons or contains an atom that increases in oxidation number. Something that is reduced gains electrons or has an atom that decreases in oxidation number. An oxidizing agent is a something that oxidizes something, meaning that the oxidation agent is itself reduced. A reducing agent is a something that reduces something else, and is itself oxidized. In this experiment, the class studied the electrochemical nature of corrosion of iron. Corrosion is the deterioration a material undergoes as a result of its interaction with its surroundings. In the test for the products of corrosion of iron, blue color was produced when Fe2+ ion reacted with potassium ferricyanide which can therefore be used to detect metal oxidation that will lead to rust. Reduction happened at the pink parts (the color produced when phenolphthalein was added to the solution containing hydroxide ions). The appearance of pink color suggests a gain in electron and preservation of hydroxide ion. Introducing a highly active metal will prevent corrosion to less reactive metal. The principle of cathodic protection is in connecting an external anode to the...
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