Question

The reduction of an oxide by aluminium is not called:
(This question has multiple correct options)
A. Ellingham’s process
B. Goldschimdt’s alumino thermite process
C. Kroll’s process
D. Van Arkel process

Answer 1

Hint: The reduction of an oxide by aluminium is achieved only by Goldschimdt’s alumino thermite process. The remaining three processes are not involved in the reduction of metal oxides by aluminium and thus, they are the correct options.

Complete step by step answer:
Let us understand all the processes one by one.
A. Ellingham’s process: This process involves a diagram plotted between change in Gibbs free energy along the y-axis and partial pressure along the x-axis. In metallurgy, the Ellingham diagram is used to predict the equilibrium temperature between a metal, its oxide, and oxygen and by extension, reactions of a metal with sulfur, nitrogen, and other non-metals. The diagrams are useful in predicting the conditions under which an ore will be reduced to its metal.
B. Goldschimdt’s alumino thermite process: Goldschimdt’s Aluminothermic reactions are exothermic chemical reactions (evolving enormous amounts of energy) and occur with the help of aluminium powder as the reducing agent at very high temperature. The reaction involved is:
${M_2}{O_3} + 2Al \to 2M + A{l_2}{O_3}$
Where, M = Metal to be reduced
C. Kroll’s process: The Kroll process is a pyrometallurgical industrial process used to produce metallic titanium from titanium tetrachloride. The reaction involved is:
$TiC{l_4}(l) + 2Mg(l)\xrightarrow{{{{800}^o}C}}Ti(s) + 3MgC{l_2}(l)$
D. Van Arkel process: This process is also known as Crystal process or Vapor phase refining. This method is based on the thermal decomposition of metal components. The process of decomposition of a compound into different substances due to the supply of heat is called thermal decomposition. Titanium metal is purified by this method. The reaction involved is:
$Ti + 2{I_2}\xrightarrow{{{{250}^o}C}}Ti{I_4}\xrightarrow{{{{1400}^o}C/Tungsten}}Ti + 2{I_2}$
The correct option is B. Goldschimdt’s alumino thermite process.

Note:
An alumino thermite process is a better way of operating metal oxides at such a higher temperature as aluminium is a good conductor of heat and provides a larger surface area to the reactants and helps in the extraction of pure metals from their corresponding metal oxides.