General Principles And Processes Of Isolation Of Elements

Gold (Au) and silver (Ag) are extracted by treating their ores with dilute NaCN solution in the presence of air. During this process, a cyanide complex is formed which gives pure metal when treated with more electropositive metal like .



This process is called Mac Arthur Forest process.

Step 1: Understanding the Thermite Reaction.
The Thermite reaction is a highly exothermic redox reaction between a metal oxide and a more reactive metal (usually aluminum). In this reaction, the more reactive metal acts as a reducing agent, displacing the less reactive metal from its oxide. The reaction produces a large amount of heat, making it useful for applications like welding.
Step 2: Identifying the components of the Thermite Reaction.
The classic thermite reaction involves iron(III) oxide (Fe₂O₃) and aluminum powder (Al). Aluminum is more reactive than iron, so it can reduce iron(III) oxide to molten iron. The balanced chemical equation for the thermite reaction is: Fe₂O₃(s) + 2Al(s) → 2Fe(l) + Al₂O₃(s) + Heat
Step 3: Evaluate the options.

• Option (a): Fe₂O₃ + Al: This combination correctly represents the classic thermite mixture, where aluminum reduces iron(III) oxide.
• Option (b): Fe₂O₃ + C: This involves carbon as a reducing agent. While carbon can reduce metal oxides at high temperatures (e.g., in blast furnaces), it's not typically referred to as the "thermite reaction" which specifically implies aluminum as the reducing agent due to its strong reducing power and the highly exothermic nature of its reactions with metal oxides.
• Option (c): Al₂O₃ + Fe: In this combination, aluminum oxide is already a stable compound, and iron is less reactive than aluminum, so iron cannot reduce aluminum oxide. No reaction would occur or it would require extreme conditions beyond a typical thermite reaction setup.
• Option (d): CuO + C: This is a reduction reaction where carbon reduces copper oxide, often used in metallurgy. However, it is not the specific "thermite reaction," which is defined by the use of aluminum as the reducing agent, especially for iron oxides.

Step 4: Conclusion.
The standard reactants for the Thermite reaction are iron(III) oxide and aluminum.