Question

Iron (III) oxide on heating with carbon monoxide gas forms solid iron and liberates carbon dioxide gas. This is a:
(A) Precipitation reaction
(B) Double decomposition reaction
(C) Synthesis reaction
(D) Redox reaction

Answer 1

Hint: Those reactions in which one atom gets oxidized and another atom get reduced and oxidation and reduction both process occurs simultaneously are known as redox reactions. Most of the chemical reactions are redox reactions because if one element is to lose electrons, then another element has to accept them.
- That reaction in which a special compound is formed by the interaction of two or more atoms in a chemical process called synthesis process. It could be exothermic or endothermic but most of the synthesis reaction is an exothermic process.
- A chemical reaction which leads to the exchange of radicals in between the aqueous solution of reacting agents is called double decomposition reaction.
- In a precipitation reaction product present in insoluble form (precipitate) and these reactions occur in aqueous medium.

Complete Solution :
Reaction of iron (III) oxide $\text{(F}{{\text{e}}_{\text{2}}}{{\text{O}}_{\text{3}}}\text{)}$ with carbon monoxide $\text{(CO)}$ forms iron $\text{(Fe)}$ and carbon dioxide $\text{(C}{{\text{O}}_{\text{2}}}\text{)}$. This reaction is an example of redox reaction in which carbon monoxide get oxidised into carbon dioxide and $\text{F}{{\text{e}}^{\text{3+}}}$ get reduced into $\text{Fe}$ atom. This redox reaction is represented by following reaction-
 $\text{F}{{\text{e}}_{\text{2}}}{{\text{O}}_{\text{3}}}\,\text{+}\,\text{3}\,\text{CO}\,\,\to \,\,\text{2Fe}\,\,\text{+}\,\,\text{3C}{{\text{O}}_{\text{2}}}$
So, the correct answer is “Option D”.

Note: If the central atom of any compound is in maximum oxidation state, then it will act as only oxidant. Since iron is present in their highest oxidation state so it will act as an oxidizing agent.
- If the oxidation state of the central element of any compound is intermediate then the compound can act as reductant as well as oxidant both.