Define corrosion and specifically describe the corrosion of iron. What does galv
ID: 999255 • Letter: D
Question
Define corrosion and specifically describe the corrosion of iron. What does galvanized mean? Use the following terms to describe the solutions (excluding water) that will be used in .1, A.2 and A.3 as acids, bases, salt, oxidizing agents, reducing agents. How is a nail manufactured? Write down the oxidation half reaction and the reduction half reaction for the corrosion of iron. Use the first step of oxidation of iron to iron (II). Include their standard potentials from your standard reduction potential table. What factors influence the corrosion of iron? Phenolphthalein will confirm the presence of which ion? Why is that ion significant and why is that ion significant to your investigations? Potassium ferricyanide illustrates the presence of which ion by forming the characteristic blue color called Prussion blue? What is significant about the presence of this ion? Introduction Each year the United States loses an estimated six billion dollars as a result of the corrosion of steel. Your company is going to be dealing heavily with iron parts. They want you to investigate the corrosion process so you can report on properties of iron and the environment that affect corrosion. You will investigate galvanized iron and iron by using nails because they are cheap materials for testing. You are to determine the factors that affect the corrosion of iron. Procedure This experiment will be set up for you and you will be collecting the results and analyzing the data. There are three parts. All students in your class and in the course will be viewing the same experimental results. Do not destroy or tamper with the materials in any way that will change the experience for students following you. Both regular nails and galvanized nails will be placed in a variety of different types of solutions. Nails will be embedded in a gel containing phenolphthalein and potassium ferricyanide. Nails will be painted or wrapped with other metals to determine the efficacy of these materials for protection against corrosion.Explanation / Answer
Corrosion: Any process of deterioration (destruction) and consequent loss of a solid metallic material through an unwanted electrochemical attack by its environment starting at its surface is called as corrosion.
Corrosion always occur at anodic areas.
7) Electrode half reaction in corrosion of iron:
Oxidation half reaction at anode: Fe ------> Fe2+ (aq.) + 2e– E0oxi = +0.44 V.
Reduction half reaction at cathode: 2H+ (aq.) + 2e– ----------> 2H
2H + ½ O2 -----------> H2O
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2H+ (aq.) + 2e– + ½ O2 -----------> H2O E0red = +1.23 V
Net reaction of corrosion cell:
Fe + 2H+ (aq.) + ½ O2 -----------> Fe2+ (aq.) + H2O E0cell = 1.67 V.
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8) Factors affecting corrosion of iron:
Corrosion is enhanced by the presence of (a) Impurities (b) Air and moisture (c) Electrolytes (d) Strains in metal like dents, scratches, welding part etc.
9) Phenolphthalein is acid base indicator and with it we can confirm presence of H+ /OH– ions. In acidic medium Phenolphthalein exhibit no colour and in presence of OH– ions it develops pink colour.
Phenolphthalein is a part of Ferroxyl indicator solution.
10) Potassium ferricyanide illustrate the presence of Fe2+ ions.
Potassium ferricyanide K3FeIII(CN)6 is a component of Ferroxyl indicator solution. Ferroxyl indicator solution turns blue in the presence of Fe2+ ions and hence its used in qualitative and quantitative estimation of Fe2+ ions using colorimeter as even a minute amount of Fe2+ developes deep intense Prussian blue colour FeII(CN)64–.
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