Question

\[\text{Fe}{{\left( \text{OH} \right)}_{\text{3}}}\]​ can be separated from \[\text{Al}{{\left( \text{OH} \right)}_{\text{3}}}\] ​ by addition of?
(A) dil.HCl
(B) NaCl solution
(C) NaOH solution
(D) \[\text{N}{{\text{H}}_{\text{4}}}\text{Cl }\!\!~\!\!\text{ }\]and \[\text{N}{{\text{H}}_{\text{4}}}\text{OH}\]​

Answer 1

Hint: Metallurgy refers to the entire scientific and technological procedure needed to separate the metal from its ore. Several chemical principles are used in the separation of an element from its mixed form. However, a few fundamental ideas apply to all metal extraction procedures.

Complete Step by Step Solution:
Aluminium, chromium, copper, iron, magnesium, nickel, titanium, zinc, and silicon are typical engineering metals. With the notable exception of silicon, these metals are most frequently used in alloys.

Understanding the iron-carbon alloy system, which includes steels and cast irons, has received a lot of attention. In applications requiring great strength and cheap cost, plain carbon steels (those that essentially solely include carbon as an alloying element) are employed because they are resistant to corrosion and weight.

Another component of the iron-carbon system is cast iron, which includes ductile iron. A non-magnetic application like directional drilling makes use of iron-manganese-chromium alloys (Hadfield-type steels).
\[\text{Al}{{\left( \text{OH} \right)}_{\text{3}}}\]and \[\text{Fe}{{\left( \text{OH} \right)}_{\text{3}}}\] can be separated using a NaOH solution.
Only \[\text{Al}{{\left( \text{OH} \right)}_{\text{3}}}\] is soluble in excess NaOH, and only \[\text{Al}{{\left( \text{OH} \right)}_{\text{3}}}\] is soluble in excess NaOH before boiling to generate sodium meta-aluminate.
Hence option (C) is correct.

Note: In the annealing process, the metal is heated and then allowed to cool very slowly. This removes stresses from the metal and creates a grain structure that is large and soft-edged, allowing the metal to bend or dent rather than break under stress. Annealed metal is also easier to sand, grind, or cut. After heating, metal is quenched, which causes the molecules to "freeze" into the extremely hard martensite state, increasing the metal's hardness.