12th Chemistry Study Plan - Metallurgy

Vocabulary-style flashcards covering the key concepts of minerals, ores, metallurgical extraction processes, and electrochemical principles of metallurgy.

Minerals

Naturally occurring substances obtained by mining which contain the metals in free state or in the form of compounds like oxides, sulphides etc.

Ores

Minerals that contain a high percentage of metal from which it can be extracted conveniently and economically; for example, Bauxite and Clay are minerals of Al, but Bauxite is its ore.

Extraction Steps

The three stages of obtaining pure metals: (i) Concentration of the ore, (ii) Extraction of crude metal, and (iii) Refining of crude metal.

Limestone ($CaCO_3$)

A basic flux used in iron extraction from $Fe_2O_3$ that decomposes into $CaO$ to react with silica ($SiO_2$) to form slag.

Slag

The fusible product formed when flux reacts with gangue; for example, $CaO + SiO_2 \rightarrow CaSiO_3$.

Froth flotation method

A method used to concentrate sulphide ores such as Galena ($PbS$) and zinc blend ($ZnS$).

Coke (as a reducing agent)

A better reducing agent than $CO$ for the reduction of $ZnO$ because the $\triangle G$ of formation of $CO$ or $CO_2$ from Coke is lower than that of $CO_2$ from $CO$.

Mond's process

A method for refining nickel where impure nickel is heated with carbon monoxide at $350\,K$ to form volatile $Ni[CO]_4$, which then decomposes at $460\,K$ to yield pure nickel.

Hall - Herold process

The electro-metallurgical extraction of Aluminium using an iron tank cathode, carbon rod anodes, and an electrolyte of Calcium Chloride, Alumina, and Cryolite at $1270\,K$.

Gangue

The rocky nonmetallic impurity associated with an ore.

Electrochemical Principle of Metallurgy

The rule that a less active element cannot reduce a more active element; success requires the electrode potential of reduction to be lower than that of the oxidant.

Standard Gibbs free energy ($\Delta G^0$)

The energy change calculated as $\Delta G^0 = -nFE^0$, where $n$ is the number of electrons, $F$ is Faraday, and $E^0$ is the standard emf.

Spontaneous Reaction (Electrochemical)

A reaction that occurs when $\Delta G$ is negative and $E$ is positive.