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प्रश्न
Observe the following picture a write down the chemical reaction with the explanation.
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उत्तर
The rusting of iron is an oxidation process. The rust on iron does not form by a simple reaction between oxygen and iron surface. The rust is formed by an electrochemical reaction. 'Fe' oxidises to Fe2O3.XH2O (Rust) is on one part of the iron surface, while oxygen gets reduced to H2O in another part of the surface. Different regions on the surface of iron become anode and cathode.
(1) Fe is oxidised to Fe2+ in the anode region.
\[\ce{Fe(s) -> Fe^{2+}(aq) + 2e^-}\]
(2) O2 is reduced to form water in the cathode region.
\[\ce{O2(g) + 4H^+(aq) + 4e^- -> 2H2O(l)}\]
When Fe2+ ions migrate from the anode region, they react with water and further get oxidised to form Fe3+ ions.
A reddish-coloured hydrated oxide is formed from Fe3+ ions. It is called rust. It collects on the surface.
\[\ce{2Fe^{3+}(aq) + 4H2O(l) -> Fe2O3.H2O(s) + 6H^+(aq)}\]
Due to various components of the atmosphere, oxidation of metals takes place, consequently resulting in their damage. This is called 'corrosion'. Iron rusts, and a reddish-coloured layer is collected on it. This is the corrosion of iron.
संबंधित प्रश्न
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Complete flow chart given below.
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| A process of forming a thick oxide of aluminium when aluminium is exposed to air. This coat makes it resistant to corrosion. Resistance can be improved by making a layer of oxide thinker. In this technique, the aluminium article is the anode, and the electrolyte is sulphuric acid. The anode reaction results in the formation of a black-coloured film of aluminium oxide on the anode. By putting appropriate dyes in the electrolytic solution, both coloured surface with the decorative finish is achieved. Kitchen articles like anodised such as pressure cookers, pans and frames of sliding windows are applications of this technique. |
- Name the anode and electrolyte used in this technique.
- How can we make aluminium articles made resistant to corrosion?
- Name the technique used to coat the aluminium articles.
