(a) What is corrosion? Explain the conditions required for the rusting of iron, and describe three effective methods use

Question

(a) What is corrosion? Explain the conditions required for the rusting of iron, and describe three effective methods used to prevent corrosion. (b) Numerical Problem: A blast furnace process uses pure Hematite ore ($Fe2O3$) to extract iron metal according to the reaction: $$Fe2O3(s) + 3CO(g) ightarrow 2Fe(s) + 3CO2(g)$$
Calculate the maximum theoretical mass of pure iron (in grams) that can be extracted from $800	ext{ g}$ of pure Hematite ($Fe2O3$). (Given atomic masses: $Fe = 56	ext{ u}$, $O = 16	ext{ u}$)

Accepted Answer

Part (a): Corrosion and Prevention Corrosion:
Corrosion is the process in which metals are gradually eaten away by the action of air, moisture, or chemicals (like acids) on their surface. Example: Rusting of iron, tarnishing of silver (formation of $Ag2S$), and formation of a green coating on copper ($CuCO3\cdot Cu(OH)2$). Conditions Required for Rusting of Iron: Presence of Air (Oxygen): Oxygen is necessary for oxidation of iron. Presence of Water/Moisture: Water vapor acts as a medium for the chemical reaction to form hydrated iron oxides ($Fe2O3\cdot xH2O$). Methods to Prevent Corrosion: Galvanization: Coating iron articles with a thin layer of zinc metal. Zinc protects iron because it is more reactive and oxidizes preferentially. Alloying: Mixing iron with other metals/non-metals to alter its properties (e.g., Stainless steel, made by mixing iron with chromium and nickel, does not rust). Painting, Greasing, or Oiling: Applying a protective coat on the metal surface prevents direct contact with air and moisture. --- Part (b): Numerical Solution Calculate Molar Mass of $Fe2O3$: Atomic mass of $Fe = 56	ext{ u}$ Atomic mass of $O = 16	ext{ u}$ $$	ext{Molar mass of } Fe2O3 = (2 	imes 56) + (3 	imes 16) = 112 + 48 = 160	ext{ g/mol}$$ Calculate Molar Mass of Iron ($2Fe$) produced: $$	ext{Mass of } 2Fe = 2 	imes 56 = 112	ext{ g/mol}$$ Stoichiometric Relationship:
From the chemical reaction: $$160	ext{ g of } Fe2O3 	ext{ yields } 112	ext{ g of } Fe$$ Mass of Iron obtained from $800	ext{ g}$ of $Fe2O3$: $$	ext{Mass of } Fe = \left( \frac{112	ext{ g}}{160	ext{ g}} ight) 	imes 800	ext{ g}$$ $$	ext{Mass of } Fe = 0.7 	imes 800	ext{ g} = 560	ext{ g}$$ Final Answer:
The maximum theoretical mass of pure iron extracted is $560	ext{ g}$.

Metals and Non-metals

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