Question

In Goldschmidt thermite process, reducing agent is
A. $Fe$
B. $Na$
C. $Ca$
D. $Al$

Answer 1

Hint: Thermite process is an exothermic reaction which liberates a large amount of heat. Practically, this method can be used to reduce all the metallic oxides, with oxides of magnesium being the only one exception.

Complete step-by-step answer: Goldschmidt thermite process is a process of extracting metals by the reduction of a metal oxide to form metal using aluminum powder, the aluminum acts as the reducing agent.
Here are few examples of the process:
Reduction of ferrous oxide to ferrous metal.
In this process reduction of ferrous oxide to ferrous metal takes place. Iron (III) oxide is mixed with aluminum powder and is ignited with a burning magnesium ribbon. Aluminum reduces iron oxide to produce a molten iron metal with the evolution of heat. The chemical reaction for the same process is represented as follows:
$F{{e}_{2}}{{O}_{3}}\,+\,2Al\to \,2Fe\,+\,A{{l}_{2}}{{O}_{3}}\,+\,heat$
Chromium oxide is reduced to chromium metal.
A mixture of chromic oxide and powdered aluminum in the ratio of $3:1$ and is ignited by magnesium ribbon. The reaction is an exothermic reaction and chromic oxide is reduced to chromium. The chemical reaction for the same is represented as below:
$C{{r}_{2}}{{O}_{3}}\,+\,2Al\,\to \,2Cr\,+\,A{{l}_{2}}{{O}_{3}}\,+\,heat$

From both the above discussed processes we can interpret that aluminum is used as reducing metal in Goldschmidt process.

Note:This property of the aluminum is used in thermite welding for joining the broken piece of the heavy iron objects like railway tracks and cracked part of the instruments and machines. Thus, it is a very important process with its wide-ranging application in the present world.