Question

No reaction takes place when granules of solid ‘A’ are mixed with a powder of solid ‘B’. However, when it is heated, a reaction starts with the evolution of heat. Product ‘C’ of the reaction settles down as a liquid metal and solid ‘D’ keeps floating over the liquid ‘C’. This reaction is sometimes used for making metals ready for use in odd places.
(i) Based on this information, make assumptions about ‘A’ and ‘B’ and corresponding deductions about ‘C’ and ‘D’ and write a balanced chemical equation for the reaction. Included in the chemical equation about physical states of the reactants and products, need of heat for starting the reaction and reaction being exothermic.
(ii) Name two types of chemical reactions to which this reaction can belong.

Answer 1

Hint: In a chemical reaction, when the energy is released in the form of heat i.eThe products formed are more stable than reactants then the reaction is exothermic whereas when the heat is absorbed during the reaction then it is said to be an endothermic reaction.

Complete answer:
Gold-Schmidt thermite process:
This process is used for the extraction of metals from those oxides which cannot be easily reduced in the presence of carbon. During the process, the metallic oxides are mixed with granules of aluminium powder which is generally known as thermite and then the reaction proceeds with only the initial ignition provided to the reaction. The process results in the formation of a mixture of aluminium oxide and respective metal. A large amount of heat is released in the process and hence, the reaction is highly exothermic in nature.
(i) Now, according to the given reaction conditions, the process follows thermite reaction and the molecular formula for ‘A’, ‘B’, ‘C’ and ‘D’ are as follows:
A $=F{e}_2{O}_3$
B $=Al$
C $=Fe$
D $=A{l}_2{O}_3$
The balanced chemical reaction for the process will be as follows:
$F{e}_2{O}_3(s)+2Al(s)\to A{l}_2{O}_3(s)+2Fe(l)$
(ii) As per the reaction it can be classified under two categories which are as follows:
Displacement reaction: It is a type of chemical reaction in which one part of the reactant gets displaced with another reactant. For the given process, the iron gets displaced by aluminium so it is a displacement reaction.
Redox reaction: A chemical reaction in which reduction and oxidation of reactants take place simultaneously is known as a redox reaction. For the given process, the reduction of iron and oxidation of aluminium takes place in a single reaction, so it is a type of redox reaction.
Hence, the two types of chemical reactions to which this given reaction can belong are displacement reaction and redox reaction.

Note:
It is important to note that, with the help of Gold-Schmidt thermite process, metals other than iron can also be obtained in their molten states. In the process, oxides like chromium oxide $C{r}_2{O}_3$ and manganese oxide $M{n}_3{O}_4$ gets reduced to form chromium metal and manganese metal respectively along with the removal of aluminium oxide.