What is an electrochemical theory of rusting of irons and give two methods of preventing the rusting of iron?
Hint: The rusting of iron is a slow process in which the iron reacts with oxygen and forms an iron oxide which is usually reddish-brown in colour. We usually study the Nernst equation and the related numerical in electrochemistry.
Complete Step-by-Step Answer:
-According to the electrochemical theory of the rusting of iron, oxidation reaction occurs at anode and reduction reaction occurs at the cathode.
-At the anode, the iron is oxidised to the ferrous ions and the electrons which are released move towards the cathode.
At the anode:
-At the cathode, the hydrogen ions are taken from the moisture that is present in the atmosphere.
-So, the reaction of water releasing hydrogen ion is:
-At the cathode:
-But the oxygen that is present on the surface of the iron is reduced by hydrogen.iron rust remover So, the reaction becomes
-Hence, by using the oxidation and reduction half-reaction we can write the overall reaction i.e.
-This ferrous ion is further oxidized by the oxygen which forms rust:
Two methods to prevent the rusting are:
-If we will paint (water-insoluble) the metal then it reduces the chances of rusting by separating the metal from the water.
-We can also use oil or grease to keep the water away from the iron.
Nernst Equation: The Nernst equation is the relation between the standard cell potential, temperature, cell potential of an electrochemical cell and the reaction quotient.
-Here, is a standard electrode potential and log Q is the reaction quotient.
-To calculate the emf, we will use the formula of the Nernst equation:
Therefore, the value of emf of the cell is 0.66V.
Note: The value of standard temperature is 298 Kelvin. Increase in the oxidation state means the oxidation whereas a decrease in the oxidation state means the reduction of a molecule. In the given question, nickel undergoes the oxidation reaction whereas copper undergoes the reduction reaction.