The paper "Atmospheric Corrosion and Galvanic Corrosion Processes" is a delightful example of a case study on science. This experiment will focus on atmospheric corrosion and galvanic corrosion processes. Atmospheric corrosion is an electrochemical process that occurs naturally on the surface of a metal. Galvanic corrosion occurred between two metals in an electrolyte. The polarity of each metal is determined by galvanic series where a more negative metal it the series becomes the anode. A current produced is due to the difference in reactivity between the two metals that give the potential of the cell (Hummel 2004). Introduction and Objectives Metals that are found in pure form are uncreative.
Reactive metals like iron are found in compound forms like oxides or sulfides and therefore metals have to be reduced using a specific process. Construction metals like iron are liable to corrosion through an electrolytic process or chemical attack (Baboian 2004). Sulphuric acid produced by some bacteria attacks iron used for reinforcement in the building. Iron may also corrode in the presence of oxygen and water. The main objective of this experiment was to find out if oxygen and water are required for corrosion to occur.
Three test tube is set up containing water, oxygen or both. Experiment A: Corrosion of metals Apparatus In this experiment, the apparatus used include: 3 x Iron nails, 1 x 250ml glass beaker, 3 x Glass Jars with lids, Hotplate, Sandpaper, Water, Silica gel and washing up liquid Procedure The glass beaker was half-filled with water and then boiled for 5-10 minutes on the hot plate. The 3 iron nails were cleaned with sandpaper then one nail was placed in a jar containing silica gel and covered with a lid.
The second nail was placed in a second jar which was filled with water. This time the jar left open. After the boiled water has been left to cool slightly, it is poured into the third glass jar to approximately ¾ full. The third nail is placed in water and a few drops of washing up liquid is dropped on the surface. The tubes were then labeled with the group name and left for 1 week before the observations were made. Corrosion of nails results Nail in silica gel – no corrosion Nail in tap water – corrosion Nail in boiled water - no corrosion. There formations of rust on nail 2 owing to the presence of both water and oxygen.
Boiled water in jar 3 had no oxygen and therefore there was no rust. Jar 1 had no moisture and therefore there was no rust. Experiment B: Corrosion of dissimilar metals Introduction and objectives Corrosion is an electrochemical process that occurs in two ways. A) It occurs when a metal reacts with its environment to form a metal oxide or other compounds.
B) It occurs when two different metals are connected electrically at one end, the other end being immersed in an electrolyte. This is called galvanic corrosion. The cell produced in this way is called a composite cell or galvanic cell. Two conditions are necessary for a galvanic cell to be formed: 1) there must be an electrolyte where the two metals are immersed. 2) The two different metals are electrically in contact. Electrochemical corrosion involves two half-cell reactions; an oxidation reaction at the anode and a reduction reaction at the cathode.
For example, half cell reactions of iron corroding in the water at near-neutral pH are represented by the following cathode and anode reactions.