Metallurgy and Non-Metals: Processes and Properties
Metallurgical Processes
Hydrometallurgy
Hydrometallurgy utilizes aqueous solutions to extract metals from ores. It involves leaching the ore with a solvent, followed by separation and purification steps to isolate the desired metal. This method is commonly used for extracting copper, nickel, and gold.
Oxidative Refining
Oxidative refining refines metals through oxidation reactions, removing impurities or transforming the metal into a more desirable form. An example is the refining of impure copper through oxidation-reduction, where impurities are oxidized and removed, leaving behind purified copper.
Electrolytic Refining
Electrolytic refining purifies metals using electrolysis. An electrolytic cell with an impure metal anode and a pure metal cathode is used. When an electric current is applied, metal cations from the anode dissolve, migrate to the cathode, and plate out as pure metal. This process is commonly used for refining copper, aluminum, and gold.
Gold and Silver Separation
Gold (Au) and silver (Ag) can be separated through the parting process. A solid mixture of both metals is boiled with nitric acid, dissolving silver and leaving gold as a residue. Iron sulfate is then added to the silver nitrate solution to precipitate silver.
Non-Metals
Phosphorus Allotropes
White Phosphorus
- Soft, translucent, waxy white solid.
- Poisonous and insoluble in water but soluble in carbon disulfide (CS₂).
- Less stable and more reactive than other forms due to angular strain.
- Exhibits chemiluminescence, glowing green in the dark.
- Reacts with oxygen to form phosphorus pentoxide: P₄ + 5O₂ → P₄O₁₀
Red Phosphorus
- Obtained by heating white phosphorus in an inert atmosphere.
- Less reactive than white phosphorus due to its polymeric structure.
- Odorless, non-poisonous powder, insoluble in water and CS₂.
- Does not readily catch fire in air.
Black Phosphorus
- Obtained by heating white phosphorus under high pressure.
- Most inactive form of phosphorus.
- Exists as a polymeric double-layer crystal lattice.
Carbon Allotropes
Diamond
- Three-dimensional polymer with carbon atoms arranged tetrahedrally.
- Very hard and dense due to strong covalent bonds.
- Purest form of carbon and the hardest known substance.
- High refractive index.
Graphite
- Two-dimensional structure with weak van der Waals forces between layers.
- Soft, greasy, and lubricating due to the ability of layers to slide over each other.
Oxoacids
The document also discusses oxoacids of chlorine and sulfur, including their chemical formulas and oxidation states.